A Novel 3-Step Tuning Fork Hearing Test; Preliminary Report on Its Clinical Utility

Abstract

It is pertinent to have a Tuning Fork Hearing Test that stand-alone can detect severities (Mild, Moderate, Severe and Profound) and the types of hearing losses (Conductive, Sensorineural, and Mixed). A novel 3-Step Tuning Fork Hearing Test (3-STFHT) was attempted for the first time that could detect both the types and the severities of hearing losses. The study was aimed to describe the method of the 3-STFHT and evaluate its clinical utility and reliability. Research Design: Hospital-based observational study of a diagnostic tool. Settings: Otorhinolaryngology Department of a tertiary care medical college hospital. Subjects: 108 adult patients (216 ears) who required hearing evaluation. Main Outcome measures: Sensitivity and specificity of novel 3-STFHT were assessed by comparing its results with the reports of pure tone audiometry in detecting the type and severity of hearing loss. The new 3-STFHT was found very effective (100% sensitivity and specificity) in detecting conductive and profound sensorineural hearing losses. The sensitivity in detecting sensorineural hearing loss was found 97%-100%. The sensitivity was observed relatively low (92%) at detecting mixed hearing loss. The overall sensitivity and specificity of the 3-STFHT in detecting the types of hearing losses was found 97% and 86% respectively. The novel 3-STFHT, which is simple and convenient, was found very effective in detecting the types and severity of hearing losses. The 3-STFHT can be an important tool in otorhinolaryngology practice and in primary care setting for detecting and screening the types and severities of hearing losses.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-022-03095-0.

Introduction

The importance and practice of Tuning Fork Hearing Tests (TFHTs) for hearing evaluation have not declined even with the advent of new generation computer-aided hearing tests. Though very old, Rinne and Weber TFHTs have stood the test of time. Simplicity is the major strength of TFHTs as the only instrument required is tuning fork. Tuning forks are readily available and inexpensive. TFHTs are easy to perform and can assist with appropriate triage and initial treatment (Shuman et al., 2013) [1].

The use of tuning forks for evaluating hearing began early in the nineteenth century (Ng and Jackler, 1993) [2]. Peculiarly this art and science of TFHTs especially Rinne and Weber still remain relevant and are practiced in twenty-first century as well. Currently, tuning forks are an important check for the pure-tone audiogram (PTA) in patients with conductive hearing loss (CHL). James Sheehy (1926–2006) of the House Group used to say to his neurotology fellows ‘‘DFTF (Don’t Forget Tuning Forks) tests’’ (Matthew and Jackler, 2018) [3].

Otologists use the Rinne test to detect conductive hearing loss (CHL) (Burkey et al., 1998; Bansal, 2018) [4, 5]. General practitioners (GPs) use TFHTs to decide whether a patient with hearing loss needs an otorhinolaryngology referral or not (Ruckenstein, 1995) [6]. The Rinne test detects CHL when PTA shows air–bone gap (ABG) of 20 dB or greater (Browning, 1987) [7]. The studies have found the Rinne test to be poor at detecting lesser than 20 dB ABGs (low sensitivity) and so can miss mild CHL (Chole and Cook, 1988; Browning and Swan,1988; Bansal, 2016) [8–10], making it unsuitable for screening purpose. It is desirable to have a TFHT which can stand-alone (individually and independently), detects all the types (conductive, sensorineural and mixed) and severities (Mild, Moderate, Severe and Profound) of hearing losses.

The present study aimed to describe a novel 3-Step Tuning Fork Hearing Test (3-STFHT) that can diagnose not only all the three types of hearing losses (conductive, sensorineural and mixed) independently but can also detect the severity of hearing loss (Mild, Moderate, Severe and Profound). The study was also aimed to evaluate the clinical utility and reliability of this novel 3-STFHT. The results of the proposed test were compared with the reports of Pure Tone Audiometry (PTA).

Materials and Methods

Approval for this study was obtained from Institutional Ethical Committee (IEC). An informed consent was obtained from every patient who participated in the study. This Hospital-based observational study of a diagnostic tool was conducted at a tertiary care medical college hospital during the period from 1st January 2018 to 30th June 2018. The consecutive 108 adult patients (216 ears) who attended the ENT out-patient-department (OPD) and required hearing evaluation, were included in this study for evaluating the clinical utility and reliability of the proposed novel 3-Step TFHT. The patients with stroke, clinically diagnosed dementia, or children < 5 years of age were excluded from the study.

Routine evaluation of enrolled patients included clinical history, endoscopic / microscopic ear examination, TFHTs and pure tone audiometry (PTA). The new 3-STFHT was done after the clinical history and physical examination of the patients. The PTA of the postgraduate resident doctors, who conducted the 3-STFHT, showed normal hearing. Impedance audiometry (IA) was done when indicated to rule out or confirm middle ear disease in patients with intact tympanic membrane. Audiometric tests were performed in double walled sound proof room. Audiologists, uninformed about the results of 3-STFHT, performed the PTA. Hearing thresholds for both air and bone conductions were recorded for each ear at 5 octave frequencies (250 to 4,000 Hz) using headphones and bone conductor vibrator of a two-channel audiometer.

The results of 3-STFHT were compared to the audiometric report to calculate sensitivity and specificity for detecting different types and severities of hearing losses. The air–bone gap (ABG) of 10 dB or greater in PTA was considered to indicate CHL. Patients with normal hearing such as patient with benign paroxysmal positional vertigo (BPPV) served as the control group.

The 3-Steps Tuning Fork Hearing Test

The novel 3-Steps TFHT was performed using a 512-Hz tuning fork in an examination room. The 3-STFHT compares the loudness and the duration of the sound of vibrating tuning fork on bone conduction. The test was conducted in both the ears separately. The non-test ear was not masked. Before conducting the test, patient was explained regarding the entire process of this new TFHT.

1. First step (Fig. 1)—Patients’ Bone Conduction (pBC): In the first-step, the base of vibrating tuning fork is firmly placed against the patient’s mastoid and the patient is asked whether s/he can hear the sound of tuning fork or not. There can be any one of the following responses:

   1. Heard—It indicates ‘Normal hearing’ or ‘mild to moderate hearing loss.’
   2. Not Heard (pBC↓): It indicates ‘Severe Sensorineural Hearing loss (SNHL)’
   3. Heard in opposite ear (pBC →): It indicates either ‘severe to Profound SNHL’ in the test ear or ‘Conductive hearing loss’ (CHL) in the opposite ear.
2. Second step (Fig. 2)—Patient’s Absolute Bone Conduction (pABC): In the second-step the external auditory canal (EAC) is occluded (thus creating conductive hearing loss) by pressing the ear tragus of patient with the finger of the examiner and the patient is asked immediately whether the loudness of tuning fork sound has increased or not. This step will detect the element of conductive hearing loss. Then the patient is requested to inform the doctor when s/he stops hearing sound of tuning fork (pABC). So this step will help in differentiating between conductive (CHL and MHL) and nonconductive hearing losses (normal hearing or SNHL). If there is conductive element in the hearing-loss, there will not be any increase in the loudness. So, there can be any one of the following responses

   1. Increase in loudness (pBC < pABC): It indicates ‘Normal hearing’ or ‘Mild to Moderate SNHL’. Patients with severe SNHL, who do not hear bone conduction (pBC↓), can start hearing the tuning fork sound on occluding the EAC (pBC↓ < pABC).
   2. No increase in loudness (pBC ≥ pABC): It indicates ‘Pure CHL’ or ‘Mixed hearing loss (MHL).
   3. Not heard (pABC↓): It indicates ‘Profound SNHL’. So the patients with profound SNHL will not hear bone conduction (pBC↓) as well as absolute bone conduction (pABC↓).

      Then the patient is requested to inform the doctor when s/he stops hearing sound of tuning fork (pABC).

3. Third step (Fig. 3)—Examiner’s Absolute Bone Conduction (eABC): When the patient stops hearing the tuning fork sounds on absolute bone conduction, examiner immediately places the base of the same tuning fork firmly against his/her own mastoid after occluding his/her EAC by pushing the tragus. Examiner notes whether s/he can hear the sound of tuning fork. This step will detect the element of SNHL. So, there can be any one of the following responses:

   1. Heard by examiner (pABC < eABC): It indicates that patient is having component of SNHL
   2. Not heard by examiner (pABC = eABC): It rules out component of SNHL.

Fig. 1.

First step—patients’ Bone Conduction (pBC) of 3-step test: the base of vibrating tuning fork is firmly placed against the patient’s mastoid

Fig. 2.

Second step–Patient’s Absolute Bone Conduction (pABC) of 3-step test: the external auditory canal (EAC) is occluded by pressing the patient’s tragus with a finger while the base of vibrating tuning fork remains firmly placed against the patient’s mastoid

Fig. 3.

Third step–Examiner’s Absolute Bone Conduction (eABC): examiner places the base of the same tuning fork firmly against his mastoid after occluding the EAC by pushing his tragus

Final Inferences

After the completion of the test, the final inferences/conclusions, which are drawn after considering the results of all the 3 steps, can be following:

• i.pBC < pABC = eABC: Patient’s bone conduction hearing (pBC) improves after occluding the EAC (pABC) but pABC is equal to the eABC. It indicates normal Hearing (Video Online Resource -1).
• ii.pBC < pABC < eABC: pBC improves after occluding the EAC (pABC) but pABC is lesser than the examiner’s ABC. It indicates mild to moderate SNHL (Video Online Resource 2)
• iii.pBC ≥ pABC = eABC: pBC hearing does not improve on occluding the EAC (pABC) and the pABC remains equal to the eABC. It indicates conductive hearing loss (CHL) (Video Online Resource 3)
• iv.pBC ≥ pABC < eABC: pBC hearing does not improve on occluding the EAC (pABC) and the pABC is lesser than the eABC. It indicates Mixed hearing loss (MHL) (Video Online Resource 4)
• v.pBC↓ < pABC < eABC: Patient does not hear the pBC sound but starts hearing after occluding the EAC (pABC) and the pABC is lesser than the eABC. It indicates severe SNHL (Video Online Resource 5)
• vi.pBC↓ = pABC↓ < eABC: Patient does not hear the pBC and pABC sounds but the examiner can hear (eABC). It indicates Profound SNHL (Video Online Resource 6)
• vii.pBC →  < pABC < eABC: Patient hears pBC sound in the opposite ear but starts hearing in the test ear after occluding the EAC (pABC) but the pABC is lesser than the eABC. It indicates Severe to profound SNHL in the test ear.
• viii.pBC →  ≥ pABC = eABC: Patient hears the pBC sound in the opposite ear but starts hearing in the test ear after occluding the EAC (pABC) but the pABC is equal to the eABC. It indicates CHL in the opposite ear.

Results

Conductive hearing loss (CHL) was observed in 56 (26%) of the 216 ears (Table 1). The mean air–bone gap (ABG) in these pure CHL ears was 33.77 dB (standard deviation = 11.28db). The range of ABG was 10 – 53.33 dB. The common causes of pure CHL were: tympanic membrane perforation (68%), tympanosclerosis (14%) and otitis media with effusion (7%). Mixed hearing loss (MHL) was found in 40 (19%) of the 216 ears. The mean ABG in these MHL ears was 23.10 dB (standard deviation = 11.71 db). The range was 10 – 51.66 dB. The common causes of MHL were: Tympanic membrane perforation (38%), tympanosclerosis (10%), and adhesive otitis media (8%). In these MHL ears, 11(28%) had normal tympanic membrane. Sensorineural hearing loss (SNHL) was seen in 54 (25%) of the 216 ears. The common causes of SNHL were: Presbycusis (60%) and vestibular disorders (22%). The associated complaint of tinnitus was observed in 10 (19%) ears with SNHL. The average time taken in conducting the 3-STFHT for one ear was found less than 30 s.

Table 1.

Showing types of hearing loss in 216 ears and their causes

Types of hearing loss (n/%)	Number of ears and percentage (n/%)	Causes of hearing loss (n/%)
Conductive hearing loss (CHL)	56/25.92%	Central perforation of tympanic membrane (CPTM) (38/67.85%); Tympanosclerosis (8/14.28%); Otitis media with effusion (OME) (4/7.14%); Adhesive otitis media (2/3.57%); Others (4:7.14%)
Mixed hearing loss (MHL)	36/16.66%	Central perforation of tympanic membrane (CPTM) (38/67.85%); Tympanosclerosis (8/14.28%); Otitis media with effusion (OME) (4/7.14%); Adhesive otitis media (2/3.57%); Others (4:7.14%)
Mild-moderate sensorineural hearing loss (SNHL)	36/16.66%	Presbyacusis (18/50%); Tinnitus (7/19.44%); Meniere’s Disease (6/16.66%); Vertigo (5/13.88%)
Severe SNHL	15/6.94%	Presbyacusis (11/73.33%); Tinnitus (3/20%); Acoustic neuroma (1/6.66%)
Profound SNHL	3/1.38%	Presbyacusis (3/100%)
Normal hearing	66/30.55%	Benign paroxysmal positional vertigo (23/34.84%); Acute vestibular neuritis (7/10.60%); Tinnitus (6/9.09%); Facial palsy (4/6.06%); CPTM (3/4.54%); Others (23:34.84%)

Tables (2 and 3) show the sensitivity and specificity of the 3-STFHT in detecting types of hearing losses. The 3-STFHT correctly gave diagnosis of nonconductive hearing loss in all (100%) of the 160 ears. The high specificity (100%) for pure CHL indicates that the 3-STFHT is unlikely to diagnose pure CHL when there is none. The 3-STFHT correctly gave diagnosis in 100% of 56 ears in which there was a pure CHL (100% sensitivity). The sensitivity of 3-STFHT decreased to 92% in ears with mixed hearing loss (MHL) while the specificity in these cases remained high (95%). Sensitivity of 3-STFHT was again found 100% in cases of severe and profound SNHL.

Table 2.

Sensitivity of new 3-step test compared to pure-tone-audiometry (number of ears: 216)

Types of hearing loss	No. of ears (3-step test/PTA)	Sensitivity (percentage) (%)
Conductive hearing loss (CHL)	56/56	100
–- 10–19 db Air–Bone Gap (ABG)	8/8	100
–- 20–29 db ABG	13/13	100
–- =  > 30 db ABG	35/35	100
Mixed hearing loss (MHL)	37/40	92.30
–- 10–19 db ABG	5/5	100
–- 20–29 db ABG	15/17	88.23
–- =  > 30 db ABG	17/18	94.44
Mild-moderate sensorineural hearing loss (SNHL)	35/36	97.22
Severe SNHL	15/15	100
Profound SNHL	3/3	100
Normal hearing	57/66	86.36
–- 5–10 dB Threshold	48/57	84.21
–- 11–25 dB Threshold	9/9	100

Table 3.

Sensitivity and specificity of 3-step test

Types of hearing loss	Sensitivity (percentage) (%)	Specificity (percentage) (%)
Conductive hearing loss (CHL)	100	100
Mixed hearing loss (MHL)	92.30	94.88
Mild-moderate sensorineural hearing loss (SNHL)	97.22	97.82
Severe SNHL	100	98.50
Profound SNHL	100	100
Overall of the 3-Step test	97.33	86.36

The sensitivity in diagnosing normal hearing was observed relatively lesser (86.36%) than other categories because 3-STFHT was detecting hearing loss of 15–25 dB which was considered as per WHO classification (hearing loss < 25 dB) normal hearing in audiometric reports. This fact brought down the overall specificity to 86% which would have been otherwise higher. The overall sensitivity (97%) of the new 3-STFHT was not affected much.

Because performing new 3-STFHT after endoscopic ear examination created the potential for bias, results from patients with tympanic membrane perforation were compared to those of patients with normal tympanic membrane (such as in Otosclerosis and Presbycusis). But the sensitivity of new 3-STFHT for patients with tympanic membrane pathology was not found greater than patients with normal tympanic membrane.

Discussion

The Rinne and Weber tests were designed to identify low-frequency unilateral conductive hearing loss. These tests would likely have missed patents with high-frequency, bilateral, and presumably sensorineural hearing losses (Yueh et al., 2003; Bagaiet al, 2006; Boatman et al., 2007) [11–13]. In contrast newly described 3-STFHT could detect not only all the 3 types of hearing losses (CHL, SNHL and MHL) and but also identify the severity of SNHL. In addition to simply distinguishing between purely conductive and purely sensorineural losses, 3-STFHT could detect a conductive component even in the presence of sensorineural hearing loss.

For any application of new test, it is critical that its individual components are reliable and valid. The reliability of 3-STFHT was found better than the reports for other tuning fork tests, highlighting its overall superiority. A recent systematic review published in 2018, reported the range of sensitivity and specificity of the Rinne test with 512-Hz tuning fork for detecting conductive hearing loss from 16 to 87% and 55% to 100%, respectively (Kelly et al., 2018) [14]. The sensitivity and specificity of 3-STFHT to detect CHL and profound SNHL was found 100%. The 3-STFHT was found 100% sensitive and 99% specific in diagnosing severe SNHL. The overall sensitivity and specificity of the 3-step test was found 97% and 86% respectively. The results of 3-STFHT are much better than the results of Rinne test reported in several other studies (Chole and Cook, 1988; Browning and Swan, 1988; Browning et al., 1989; Burkey et al., 1998) [4, 7, 8, 13]. With 10–19 dB ABG, Burkey et al. (1998) found the sensitivity of 512-Hz Rinne test 49–59% which increased to 92–96% with ≥ 30 dB ABG [4]. In contrast the present study on 3-STFHT found 100% sensitivity and specificity in detecting pure CHL irrespective of the extent of ABG (Tables 2 and 3). Browning and Swan (1988) study on sensitivity and specificity of Rinne tuning fork test showed 69% sensitivity of Rinne test in detecting CHL when air–bone gap was 15–20 dB [13]. While in present study, sensitivity and specificity of 3-STFHT in detecting even 10 dB ABG conductive hearing loss was found 100%.

The proportion of false negatives is reduced at the expense of false positives and vice versa. A clinically acceptable combination of sensitivity and specificity values will depend on the consequences of missing the diagnosis of true conductive components (false negatives) and wrongly diagnosing conductive loss in those ears which have true sensorineural hearing loss (false positives). A high false-negative rate could lead to morbidity or mortality (such as in cholesteatoma), if left undetected and untreated (Munz et al., 1992; Spilsbury et al., 2010) [15, 16]. A high false-positive can result in unnecessary anxiety and incur expenses due to the visit to a specialist (as the management of CHL may need surgical intervention). The chance of getting CHL with 3-STFHT in patients without CHL was reported nil.

The reports studying the sensitivity and specificity of Rinne test found equivocal responses, the inclusion and exclusion of which could affect the overall results (Browning and Swan, 1988; Browning et al., 1989; Burkey et al., 1998) [4, 7, 13]. In present study, there was no confusion regarding the equivocal responses as there was no scope of equivocal responses in 3-STFHT. We employed 512-Hz tuning fork for our study on 3-STFHT as earlier reports (Browning and Swan, 1988; Browning et al., 1989; Burkeyet al, 1998) had found the 512-Hz tuning fork to be a very sensitive instrument for the detection of conductive hearing losses [4, 7, 13].

The TFHTs were found most sensitive when performed by an experienced physician (Burkeyet al, 1998) [4]. During the initial part of our study, this new 3-STFHT was performed by the first author who came out with the idea of this test. After 15–20 cases, postgraduate residents developed experience and confidence in the test and started having consistent results which reduced the need for confirmation from the side of experienced consultant (first author).

Contrary to the general belief, overall sensitivity of Rinne test was not reported to be improved by masking (Miltenburg, 1994) [17]. The 3-STFHT was also done without masking the opposite ear. Moreover 3-step test inquired from the patients whether they could hear the tuning fork sound in the opposite ear in the first step itself. The study of Burkey et al. (1998) found the mean sensitivity of unmasked Rinne test with 512-Hz tuning fork higher for experienced physicians than for otology fellows [4]. In that study, masking was not found affecting the test specificity.

Most professional organizations including the US Preventive Services Task Force endorse the screening as the most hearing losses in elderly people can be managed by primary care clinicians (Yueh et al., 2003) [18]. In randomised trials, patients with SNHL have been shown to be benefitted by hearing aid fittings (Yueh et al., 2003) [18]. The present study shows the following three reasons why the 3-step test can become popular as a diagnostic and screening procedure for detection of the types CHL, SNHL and MHL) and severity of hearing losses (Mild, Moderate, Severe and Profound).

• First, the study showed that after some experience the 3-STFHT can be very accurate (100% sensitivity and specificity) at detecting pure CHL and profound SNHL and 97%-100% sensitive in detecting SNHL.

• Second, the study showed very high overall accuracy (sensitivity 97% and specificity 86%) in correctly diagnosing pure CHL, SNHL, and MHL.

• Third, we believe that the readily available 512-Hz tuning fork, convenience of procedure and its quickness (as average test time was less than 30 s) can make it popular and widely acceptable.

In an otology/audiology practice where audiometric and impedance testing are done routinely to differentiate between conductive (pure CHL and MHL) and nonconductive hearing losses, the 3-STFHT can be highly useful. The 3-STFHT has the simplicity of Rinne test with an additional benefit of detecting the types and severity of hearing losses.

The strength of 3-STFHT was that it rarely detected CHL when there was none. The other strong point of 3-STFHT was that the test was found 100% sensitive and specific at detecting pure CHL even when the ABG was only 10 dB and the Weber test was not performed. These results show that the 3-STFHT can be a reliable indicator of pure CHL, SNHL and MHL and for confirming the audiometric results. In primary care settings, 3-STFHT can be used as a screening measure to detect the types (pure CHL, SNHL and MHL) and severity of hearing losses.

The results from this study indicate that to obtain consistent and reliable outcomes, some practice and experience will be required to gain confidence in the 3-STFHT. So not only in otology/audiology clinics but also in primary care settings, 3-STFHT can be used reliably as a screening measure to detect the types (CHL, SNHL and MHL) and severity of hearing loss (Mild, Moderate, Severe and Profound). Nevertheless, as reported by Ruckenstein (1995), it is important to combine the findings from patient’s history, ear examination and TFHTs to decide when otologic referral is necessary.

In a patient with hearing loss and normal tympanic membrane if 3-STFHT shows a conductive element, there is very high possibility that there will be a conductive component in the hearing loss because of 3-STFHT's high specificity. If the pure-tone audiogram does not show a conductive element then the position should be reviewed and impedance testing needs to be conducted.

One limitation of our study was the inclusion of only two testers (AS and BG both P.G. residents) who were working directly under the observation of the first author (MB). Although this allowed us to control for inter-examiner variability, our results cannot be generalized across examiners. Although our findings suggest that the presence of a conductive element can be predicted using the 3-STFHT alone, these should be verified in a larger population. Ideally, the validity of the proposed test should be further evaluated in different types of hearing losses.

Conclusion

The 512-Hz 3-STFHT can be a very effective tool not only in detecting the types of hearing loss (CHL, SNHL and MHL) but also in knowing the severities of hearing loss (mild, moderate, severe and profound). There is no need of masking. In an otology practice, the 3-STFHT can prove to be an important tool for detecting CHL, SNHL and MHL and as a validation of audiometric findings. In primary care settings, the 3-STFHT can be used as a part of screening program for detecting types and severities of hearing losses. Further studies with larger sample size would be required to support the outcomes of this new 3-STFHT.

Key message

A novel 3-Step Tuning Fork Hearing Test (3-STFHT) was attempted for the first time that could detect both the types and the severities of hearing losses. The novel 3-STFHT, which is simple and convenient, was found very effective in detecting the types and severity of hearing losses. The 3-STFHT can be an important tool in otorhinolaryngology practice and in primary care setting for detecting and screening the types and severities of hearing losses.

Supplementary Information

Below is the link to the electronic supplementary material.

Funding

The authors did not receive support from any organization for the submitted work. No funding was received to assist with the preparation of this manuscript. No funding was received for conducting this study. No funds, grants, or other support was received.

Declarations

Conflict of interests

The authors have no relevant financial or non-financial interests to disclose. The authors have no competing interests to declare that are relevant to the content of this article. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. The authors have no financial or proprietary interests in any material discussed in this article.

Informed consent

Informed consent was obtained from all individual participants included in the study.