Table 1.
Summary of the included studies.
| Study | Clinical population | OAE protocol | CAS | MEMR control | MOC reflex | Conclusions |
|---|---|---|---|---|---|---|
| Veuillet et al. (1999) | Learning-impaired (n = 14) | CEOAE; linear; 60-72 dB SPL; unknown SNR; MOC reflex was computed by equivalent attenuation method | 30 dB SL BBN | Unknown | Reduced relative to controls; relatively lower OAE levels in the learning-impaired group; right ear was more affected | A deficit in inhibitory MOC mechanisms could reflect a more central dysfunction |
| Muchnik et al. (2004) | APD/LD (n = 15) | TEOAE; non-linear; 74 dB SPL; 3 dB SNR | 40 dB SL BBN | Clinical ART | Lower compared with control group; more affected in 8.0–20.48 ms range; no relationship between APD test outcomes and MOC reflex strength; higher OAE levels in APD | Reduced auditory inhibitory function in some children with APD who also had difficulty with hearing in noise |
| Clarke et al. (2006) | SLI (n = 18) | TEOAE; linear; 60 dB SPL; unknown SNR | 65 dB SPL BBN | Clinical ART | No group differences; no right vs. left ear differences; MOC reflex in right ear and expressive grammar scores were related | No relationship between MOC activity and language impairment |
| Sanches and Carvallo (2006) | APD (n = 36) | TEOAE; linear 60 dB and non-linear 60–80 dB SPL; unknown SNR | 60 dB SPL BBN | Unknown | No group differences but lower prevalence of MOC effect in APD group; no effect of linear vs. non-linear OAE recording method; classifying the APD group based on speech-in-noise scores did not change the study outcomes | Abnormal MOC inhibition was significantly more common in the APD groups than in the control group |
| Veuillet et al. (2007) | Dyslexics (n = 38) | CEOAE; 57–69 dB SPL; 4 dB SNR68 | 30 dB SL BBN | Unknown | Stronger reflex in the right than the left ear in controls, but predominated in the left ear in dyslexics; reduced reflex in the right ear in dyslexics; MOC reflex asymmetry changed following training | Deficits in categorical perception were accompanied by abnormalities in MOC reflex asymmetry in dyslexics |
| Burguetti and Carvallo (2008) | APD (n = 38) | TEOAE; unspecified level; linear; 0–5 dB SNR | 60–65 dB SPL BBN | Clinical ART | No significant group differences; tendency for stronger reflex in the control group; right ear advantage in controls, but left ear advantage in the APD group | Lack of clear evidence for a reduced MOC inhibition in APD |
| Garinis et al. (2008) | LD (n = 18) | TEOAE; linear; 60 dB SPL; 3 dB SNR | 60 dB SPL BBN | Clinical ART | Relatively lower reflex in the left ear in LD; for the right ear, CAS caused an enhancement in OAE levels for LD but a reduction for controls; lower OAE levels in LD | MOC mechanisms differ in adults with LD compared to those with typical learning abilities; this study included adult participants |
| Yalçinkaya et al. (2010) | Listening problem (n = 12) | TEOAE; non-linear 83 dB SPL; 3 dB SNR | 40 dB SL | Clinical ART | Reduced reflex at 1000–2000 Hz band in the study group; lower OAE levels for the right ear in the study group | Lower MOC inhibition may be associated with listening problems |
| Butler et al. (2011) | APD (n = 8) | DPOAE; f2/f1 = 1.22 and 1.10; f2 = 2,3 and 4 kHz; L1/L2 = 60/55 dB; SNR > 6 dB | 60 dB SPL | ART ≥ 70 dB HL | No group differences in MOC reflex, OAE level, or noise floor | No support for an efferent hypothesis for APD |
APD, auditory processing disorder; ART, acoustic reflex threshold; BBN, broad-band noise; CAS, contralateral acoustic stimulation; CEOAEs, click-evoked otoacoustic emissions; DPOAEs, distortion product otoacoustic emissions; LD, learning disability; SLI, specific language impairment; SNR, signal-to-noise ratio; TEOAE, transient-evoked otoacoustic emissions.