Table 3. Descriptive summary of extracted data from the 13 included articles.
| Study | Design | Participants | Training | Outcomes | Main findings | Compliance and follow-up | ||||
| Hearing loss and hearing device | n, age and sex | Stimuli | Frequency and duration | Laboratory- or home-based training? | (bold indicates trained stimuli) | Trained stimuli | Untrained stimuli | |||
| Fu et al. 2004 [36] | Repeated measures | 7 pre-lingually and 3 post-lingually deafened adults. Existing cochlear implant users. | n = 10. 25–60 years, mean = 42.4 years. 4 male, 6 female. | Phonetic (vowel and consonant contrast) training with monosyllabic word, tailored to baseline performance. | 1×1–2 hour sessions per day, 5 days per week, duration not reported. | Home | Consonant and vowel recognition, voice gender discrimination, HINT sentences. | Improvements for vowel (14.4%***, 10/10 participants tested) and consonant (13.0%**, 7/10 tested) recognition. No improvement in voice gender recognition (0.3%, 7/10 tested). | Improvements in open set word-in-sentence recognition on HINT (27.9%**, 3/10 participants tested). | Compliance not reported. No follow-up assessment. |
| Burk et al. 2006 Experiment 2 [37] | Repeated measures | Mild to moderate bilateral SNHL. | n = 7. 65–75 years, mean = 69.6 years. 3 male, 4 female. | Right ear only, (open- or closed-set) monosyllabic AB words in noise (0 dB SNR), adjusted for audibility relative to individuals audiogram. | 7×1 hour sessions in total over approx. 2 weeks (max. 3 days between sessions). | Laboratory | Trained AB word recognition, untrained AB word recognition. | Improvements in open-set (45.3%***) and closed-set (11.0%*) trained AB word recognition. No significant generalisation to trained AB words presented by untrained talkers. | Improvements in open-set untrained AB word recognition (6.9%*), no improvement for closed-set untrained AB word recognition (average improvement = 5.3%, ns). No significant generalisation to untrained AB words presented by a trained talker. | Compliance not reported. 5/7 participants returned 6 months post-training (Experiment 3). Performance remained significantly improved from baseline for trained open-set AB words (25.3%*), yet significantly worse than immediate post-training levels. |
| Burk et al. 2006 Experiment 3 [37] | Non-randomised controlled trial (control group = 9 young listeners, normally hearing. | Mild to moderate bilateral SNHL (5/7 participants from Experiment 2). | n = 5. 68–75 years, mean = 71.0 years. 2 male, 3 female. | Right ear only, (open- or closed-set) monosyllabic AB words in noise (0 dB SNR), adjusted for audibility relative to individuals audiogram. | Less than 1 hour (top-up training). | Laboratory | Trained AB words recognition, trained AB words in TIMIT sentences, untrained AB words in TIMIT sentences. | Trained AB words returned to within 95% critical difference of immediate post-training scores (Experiment 2). No significant improvements in trained AB words in TIMIT sentences. | No improvements in untrained AB words in TIMIT sentences. | Compliance not reported. No follow-up assessment. |
| Stecker et al. 2006 Experiment 1 [38] | Randomised controlled trial crossover (control group trained second). | Mild to moderate bilateral SNHL. New hearing aid users. | n = 23. 50–80 years, mean = 69.0 years. 23 male, 0 female. Immediate training (IT) n = 12. Delayed training (DT) n = 11. | Adaptive nonsense syllable (NST) identification in noise. | 5×35–70 minute sessions per week for 8 weeks. | Home | NST, R-SPIN. | IT group: Improvement of 10.6%*** in NST identification. DT group: 8.8%*** improvement. Trained NST improvements were shown to generalise to untrained voices (p<.001). Significant improvement in performance for trained NST presented by untrained talkers***. | 5 subjects from the IT group and 6 from the DT group were tested on the R-SPIN. Average improvement of 3.3% (ns) attributed to lack of power. | 92.5% average compliance reported. Participants completed 29–44 days of training out of a required 40 days. Mean training days = 37, mode = 40. No significant decrement (−1.1%, ns) from post-training performance for NST syllable identification at an 8 week follow-up assessment. |
| Stecker et al. 2006 Experiment 2 [38] | Repeated measures | Mild-moderate bilateral SNHL. Existing hearing aid users. | n = 8. 61–75 years, mean = 67.7 years. Sex not reported. | Adaptive nonsense syllable (NST) identification in noise. | 5×35–70 minute sessions per week for 8 weeks. | Home | NST. | Improvement (p<.01) in NST identification, although to a lesser degree than new hearing aid users in Experiment 1. | - | Compliance not reported. No significant decrease in performance for NST syllable identification at a 2 months post-training follow-up. |
| Sweetow and Henderson-Sabes, 2006 [39] | Randomised controlled trial crossover (control group trained second). | Normal hearing to severe SNHL. n = 56 existing hearing aid users. | n = 89. 28–85 years. Immediate training group (IT) n = 56, mean age = 63.2 years, sex not reported. Delayed training group (DT) n = 33, mean age = 64.2 years, sex not reported. | Listening and Communication Enhancement (LACE). | 5×30 min sessions per week for 4 weeks. | Home | LACE, QuickSIN, HINT sentences, Listening Span, Stroop, HHIA/E, CSOA. | Improvements shown for all LACE measures overall: Speech/Babble, Time Compression, Competing Speaker, Auditory Memory and Missing Word (all p<.05). Non hearing aid users (n = 9) only improved significantly in Speech/Babble and Competing Speaker (p<.05). | Improvements in the trained group (Group 1, n = 38) for QuickSIN 45 dB (−2.2 dB SNR***) QuickSIN 70 dB (−1.5 dB SNR***), Listening Span (.5 sentences*), Stroop (7.5 points**), HHIA/E (7.5 points/17%**) and CSOA (.14**). No significant improvement in HINT (where the control group also showed improvement). | 73% compliance (65/89 participants enrolled completed the training, immediate training group n = 38/56, delayed training group n = 27/33). Improvements are maintained for participants tested on QuickSIN and HINT (n = 42/65 tested), HHIA/E and CSOA (n = 31/65 tested) 1 month post-training. No statistical tests reported. |
| Burk and Humes, 2008 [40] | Repeated measures | Mild to moderate SNHL. | n = 8. 58–78 years, mean = 69.5 years. 4 male, 4 female. | Right ear only - Recognition of 75 lexically hard and 75 lexically easy CVC monosyllabic words (difficulty switched at training mid-point), presented in noise and adjusted for audibility relative to the audiogram. | 20–24 sessions (average 3 per week), for approx. 12 weeks. | Laboratory | Trained CVC word recognition, untrained CVC word recognition, VAST sentences. | Improvement in exically hard trained words for open-set (47.4%***) and closed-set recognition (16.4%***). Lexically easy words also improved for both open-set (40.4%***) and closed-set recognition (17.2%***). Improvements for hard words (40.2%***) and easy words (35.0%***) when presented by unfamiliar talkers. | No improvements were shown for recognition of untrained words. Some individual but no group improvements on trained words embedded within VAST sentences. | Compliance not reported. Improvements in trained word recognition were maintained across weekly follow-up assessments beginning 7 weeks post-training and lasting for 7–8 weeks (no statistical tests reported). |
| Miller et al. 2008 [41] | Randomised controlled trial (hearing aid users: n = 8 trained, n = 4 controls. cochlear implant users: n = 8 trained, n = 8 controls). | Existing hearing aid users: n = 11 SNHL, n = 1 mixed loss at low frequencies. Existing cochlear implant users: n = 10 adult onset, n = 6 child onset deafness. | n = 28. n = 12 hearing aid users: 26–90 years, mean = 76.3 years.Sex not reported. n = 16 cochlear implant users: 35–81 years, mean = 55.5 years. Sex not reported. | Speech perception assessment and training system (SPATS): Syllable constituents and sentences (in quiet and in babble). | 2×2 hour sessions per week for 6 weeks. | Laboratory | SPATS, HINT sentences, CST-AV, CST-A, CID sentences, W22 words, CNC. | Improvements in SPATS (nuclei and onset) in quiet and for hearing aid users (average 8% improvement), and for cochlear implant users (average 6% improvement). Improvement for pooled hearing aid and cochlear implant trained participants of 11% (average 7% improvement in quiet and 15% in noise), relative to controls. | Improvements in CST-AV, CID W22, CNC for hearing aid users (when HINT and CST-A data removed) of around 10%. Averaged over all measures, trained hearing aid users improved by 8% compared to controls. Improvements in all measures for cochlear implant users, with greatest gains for HINT in quiet. Overall, trained cochlear implant users improved by 13% relative to controls. Pooled trained participants improved on average 10% on untrained outcomes relative to controls. Statistical tests not presented for individual outcome measures. | Compliance not reported. No follow-up assessment. |
| Humes et al. 2009 [42] | Repeated measures | Older adults with hearing impairment n = 10 trained using protocol 1: High frequency pure-tone average (HfPTA) across 1, 2, 4 k Hz mean = 31 dB HL, SD 9.6. n = 6 trained using protocol 2: HfPTA mean = 26.4 dB HL, SD 14.1. | n = 16. Protocol 1: n = 10. Mean age = 70.2, SD = 6.8 years. 7 male, 3 female. Protocol 2: n = 6. Mean age = 72.8, SD = 7.6 years. 5 male, 1 female. | Closed set word identification training in noise (4 speakers). Protocol 1: repeated in blocks of 2400, Protocol 2: repeated in blocks of 600. | 24×75–90 minute sessions over 8–12 weeks. | Laboratory | Trained frequent word recognition, CID sentences, VAST sentences, Frequent phrases. | Significant improvements shown for frequent word identification of around 18 rationalised arcsine unites (RAUs)*. | Significant improvements in CID sentences, VAST sentences and frequent phrases. Average improvements of between 12–20 RAUs*. | 81% compliance reported (13/16 participants completed the requested training duration) across two training protocols. Non-complaint participants retained in main analyses. No follow-up assessment. |
| Stacey et al. 2010 [43] | Repeated measures | n = 2 pre-lingual, n = 10 post-lingual, n = 1 pre/post-lingually deafened adults. Existing cochlear implant users. | n = 11. 23–71 years, mean = 54.8 years. 6 male, 5 female. | 2-AFC discrimination of words presented acoustically from options presented visually. | 1 hour per day for 3 weeks. | Home | Trained word and sentence (IEEE/SPIN) recognition, IEEE sentences, BKB sentences, Consonant test, Vowel test, GBI. | No improvement in trained stimuli (trend for improvement in trained sentences identified with polynomial contrasts). | Improvement in consonant test (8.06%*). | 73% compliance reported (8/11 participants completed the requested training duration). Three participants excluded having completed just five hours of the requested 15 hours training.No follow-up assessment. |
| Tyler et al. 2010 Experiment 1 [44] | Repeated measures | Post-lingually deafened adults. Existing cochlear implant users. | n = 3. 43–63 years, mean = 60.3 years. 1 male, 2 female. | 8-loudspeaker presentation of sound localization and Spondee words in babble. | 1–3 months. Details of training sessions not reported. | Home | Spondee word recognition, Sound localization, CNC, CUNY sentences, HINT sentences. | Improvement in sound localisation for subject 1 (reduction in RMS error of 7o***). Improvements in the adaptive spondee-in-noise test for subject 1 (p<.01– p<.001) and subject 2 (p<.001) | Improvement in HINT (32%***) for subject 1. Improvements in CNC in noise recognition (4%*) and HINT sentences (36%***) for subject 2. | Compliance not reported. Retention of improvements in sound localisation and HINT at 2 and 7 months post-training for subject 1, other participants not tested. No statistical tests reported. |
| Tyler et al. 2010 Experiment 2 [44] | Non-randomised controlled trial | Post-lingually deafened adults. Existing cochlear implant users. | n = 9. Trained: n = 3. 63–77 years, mean = 68.7 years. 1 male, 2 female. Controls: n = 6. Age not reported. 3 male, 3 female. | 2-loudspeaker presentation of sound localization and Spondee words in babble. | 1–3 months. | Home | Sound localization, Spondee word recognition. | Improvements in localization scores were shown for subjects 1 (p<.001) and 2 (p<.01). Significant improvements in recognition scores were shown for subject 1 (p<.05) and subject 3 (p<.05). | - | Compliance not reported. No follow-up assessment. |
| Oba et al. 2011 [45] | Repeated measures | Post-lingually deafened. Existing cochlear implant users. | n = 10. 46–78 years, mean = 66.4 years. 4 male, 6 female. | Sound Express: Digits-in-noise (speech babble and steady noise). | 5×30 minute sessions per week for 4 weeks. | Home | Digit-in-noise (babble), HINT sentences, IEEE sentences. | Improvements in digits-in-noise (steady noise) SRT of −2.8** dB and digits-in-noise (babble) of −4 dB***. | Improvements for HINT sentences in babble (−2.9 dB SRT**) and IEEE sentences in steady noise (improvement in % correct of 1.5%*) and in babble (9.2%*). | 100% compliance reported. Performance remained significantly improved from baseline at a 1 month post-training follow-up for all improved measures (p<.001). |
| Barcroft et al. 2011 [46] | Repeated measures | Mild-moderate bilateral SNHL. Existing hearing aid users. | n = 69. Multi-talker training group (MTG): n = 35,18 male, 17 female. Males: 18–87 years, mean = 67 years. Females: 23–89 years, mean = 62 years. Single-talker training group (STG): n = 34,21 male, 13 female. Males: 46–89 years, mean = 70 years. Females: 22–87 years, mean = 64 years. | I hear what you mean – listening comprehension activities in four-talker babble. | 12×1 hour sessions, twice a week for 6 weeks. | Laboratory | Iowa consonant test, Build-a-sentence test, Four-choice discrimination test. | - | Improvement in four-choice discrimination test (13.7% points***), with scores for the single talker version significantly greater than those on the multi-talker version (p>.001). No effect of STG/MTG training group. Results from other outcomes not reported. | Compliance not reported. No follow-up assessment. |
| Ingvalson et al. 2012 [47] | Repeated measures | Post-lingually deafened. Existing cochlear implant users. | n = 5. 50–85 years, mean = 71.4 years. 2 male, 3 female. | Seeing and Hearing Speech program (vowel and consonant identification in words, sentences and phrases in multi-speaker babble). | 4×1 hour sessions spread over four days. | Laboratory | Vowel and consonant recognition in words, phrases and sentences, SSQ, QuickSIN, HINT. | - | Improvement in HINT in quiet**, HINT at +15 dB SNR** and QuickSIN*. | Compliance not reported. Improvements in HINT and QuickSIN maintained at a 4-day post-training follow-up assessment. |
| Zhang et al. 2012 [48] | Repeated measures | Post-lingually deafened. Existing bimodal hearing aid and cochlear implant users. | n = 7. 51–78 years, mean = 64 years. 2 male, 5 female. | Sound Express: phoneme contrast training (vowels and consonants), for six subjects and monosyllabic word identification in multi-speaker babble for one subject. | 1 hour per day, 5 days a week for 4 weeks. | Home | Vowel and consonant recognition, CNC words, AzBio sentences, Voice gender and emotion identification. | - | Improvements for six out of seven participants for speech recognition: Vowel (8.6%*) and consonant (9.8%*) identification, CNC words (14.9%*). No improvements were shown for AzBio sentences (8.3%, ns), nor for pitch-related performance (voicegender and emotion identification) | 100% compliance reported. Improvements largely maintained at a one-month follow-up (vowel, consonant and CNC word recognition follow-up scores were significantly greater (p<.05) than baseline scores at the follow-up assessment). |
Data for normally hearing participants are omitted from this table [42].
− = no data reported, *p<.05, **p<.01, ***p<.001. MSB = multi-speaker babble, SNHL = sensorineural hearing loss; SNR = signal to noise ratio, SRT = speech reception threshold, RAU = rationalised arcsine unit [49]; Adaptive spondee words in babble test [50]; Adaptive 12-choice spondee words with multiple jammers test [51]; AzBio sentences [52]; BKB = Bamford-Kowal-Bench sentence lists [53]; Build-a-sentence test [54]; CID Everyday Sentences = Central Institute for the Deaf everyday sentences [55]; CID W22 = Central Institute for the Deaf word lists [56]; CNC = consonant-vowel nucleus-consonant monosyllables [57]; CNC words [58]; Consonant recognition [59]; CSOA = Communication Scale for Older Adults [60]; CST-A = Connected Speech [audio] test [61]; CST-AV = Connected Speech [audio-visual] test [61]; CUNY = City University of New York sentences [62]; Everyday sounds localization test [63]; IEEE Sentences [64] Four-choice discrimination test [46]; GBI = Glasgow benefit inventory [65]; HHIA = Hearing handicap inventory for adults [66]; HHIE = Hearing handicap inventory for the elderly [67]; HINT = Hearing in noise test [68]; Iowa consonant test [69]; LACE = Listening and Communication Enhancement, [39]; Listening span test [11]; NST = Nonsense syllable test [70]; QuickSIN [70]; R-SPIN = Revised speech perception noise test [71]; SPATS = [72]; SPIN = Speech perception in noise test [73]; SSQ = Speech, Spatial and Qualities of Hearing Scale [74]; Stroop Color Word test [75]; TIMIT sentences [76]; VAST = Verb and sentence test [77]; Vowel recognition [78].