Jacek Smurzynski

The relationship between distortion product otoacoustic emissions and extended high-frequency audiometry in tinnitus patients. Part 1: Normally hearing patients with unilateral tinnitus

Summary Background The aim of this study was to evaluate distortion product otoacoustic emissions (DPOAEs) and extended high-frequency (EHF) thresholds in a control group and in patients with normal hearing sensitivity in the conventional frequency range and reporting unilateral tinnitus. Material/Methods Seventy patients were enrolled in the study: 47 patients with tinnitus in the left ear (Group 1) and 23 patients with tinnitus in the right ear (Group 2). The control group included 60 otologically normal subjects with no history of pathological tinnitus. Pure-tone thresholds were measured at all standard frequencies from 0.25 to 8 kHz, and at 10, 12.5, 14, and 16 kHz. The DPOAEs were measured in the frequency range from approximately 0.5 to 9 kHz using the primary tones presented at 65/55 dB SPL. Results The left ears of patients in Group 1 had higher median hearing thresholds than those in the control subjects at all 4 EHFs, and lower mean DPOAE levels than those in the controls for almost all primary frequencies, but significantly lower only in the 2-kHz region. Median hearing thresholds in the right ears of patients in Group 2 were higher than those in the right ears of the control subjects in the EHF range at 12.5, 14, and 16 kHz. The mean DPOAE levels in the right ears were lower in patients from Group 2 than those in the controls for the majority of primary frequencies, but only reached statistical significance in the 8-kHz region. Conclusions Hearing thresholds in tinnitus ears with normal hearing sensitivity in the conventional range were higher in the EHF region than those in non-tinnitus control subjects, implying that cochlear damage in the basal region may result in the perception of tinnitus. In general, DPOAE levels in tinnitus ears were lower than those in ears of non-tinnitus subjects, suggesting that subclinical cochlear impairment in limited areas, which can be revealed by DPOAEs but not by conventional audiometry, may exist in tinnitus ears. For patients with tinnitus, DPOAE measures combined with behavioral EHF hearing thresholds may provide additional clinical information about the status of the peripheral hearing.

Origin of suppression of otoacoustic emissions evoked by two-tone bursts.

Otoacoustic emission (OAE) data recorded for tone bursts presented separately and as a two-tone burst complex, that had been reported previously [Yoshikawa, H., Smurzynski, J., Probst R., 2000. Suppression of tone burst evoked otoacoustic emissions in relation to frequency separation. Hear. Res. 148, 95-106], were re-processed using the method of adaptive approximations by matching pursuit (MP). Two types of stimuli were applied to record tone burst OAEs (TBOAEs): (a) cosine-windowed tone bursts of 5-ms duration with center frequencies of 1, 1.5, 2 and 3kHz, (b) complex stimuli consisting of a digital addition of the 1-kHz tone burst together with either the 1.5-, 2- or 3-kHz tone burst. The MP method allowed decomposition of signals into waveforms of defined frequency, latency, time span, and amplitude. This approach provided a high time-frequency (t-f) resolution and identified patterns of resonance modes that were characteristic for TBOAEs recorded in each individual ear. Individual responses to single-tone bursts were processed off-line to form sum of singles responses. The results confirmed linear superposition behavior for a frequency separation of two-tone bursts of 2kHz (the 1-kHz and 3-kHz condition). For the 1, 1.5-kHz condition, the MP results revealed the existence of closely positioned resonance modes associated with responses recorded individually with the stimuli differing in frequency by 500Hz. Then, the differences between t-f distributions calculated for dual (two-tone bursts) and sum-of-singles conditions exhibited mutual suppression of resonance modes common to both stimuli. The degree of attenuation depended on the individual pattern of characteristic resonance modes, i.e., suppression occurred when two resonant modes excited by both stimuli overlapped. It was postulated that the suppression observed in case of dual stimuli with closely-spaced components is due to mutual attenuation of the overlapping resonance modes.

Wpływ ubytków słuchu w zakresie wysokich częstotliwości na otoemisje produktów zniekształceń nieliniowych ślimaka u osób z szumami usznymi i prawidłowym progiem słyszenia w zakresie 0,25–8 kHz

AIM OF THE STUDYnTo evaluate the influence of high frequency hearing loss (> 8000 Hz) on distortion product otoacoustic emissions registered in the frequency range from 0,5 to 8 kHz.nnnMATERIAL AND METHODSn280 ears with tinnitus and normal hearing (0.25-8 kHz) divided into 3 groups depending on the degree of high frequency hearing loss: group A--hearing threshold up to 20 dB for 10, 12.5, 14 and 16 kHz (68 ears); group B--hearing threshold 25-40 dB HL for at least one of four EHfs (93 ears); group C--hearing threshold above 40 dB HL for at least one of four EHFs (119 ears). For each group mean audiogram and DP-gram were obtained and statistical analysis was used for comparison across these groups.nnnRESULTSnMean DPOAE values in group C were significantly lower in comparison with group A for the frequency range 2-8 kHz, and in comparison with group B were significantly lower for the frequency range 4-8 kHz.nnnCONCLUSIONSnHigh frequency hearing loss (above 8 kHz) has a relevant influence on distortion product otoacoustic emissions registered at frequencies below 8 kHz in tinnitus patients. The greater is hearing loss above 8 kHz, the lower is DPOAE value below 8 kHz.

MUSICAL TRAINING INFLUENCES AUDITORY TEMPORAL PROCESSING

Background: A link between musical expertise and auditory temporal processing abilities was examined. Material and methods: Trained musicians (n=13) and non-musicians (n=12) were tested on speech tasks (phonetic identification, speech recognition in noise) and non-speech tasks (temporal gap detection). Results: Results indicated musicians had shorter between-channel gap detection thresholds and sharper phonetic identification functions, suggesting that perceptual reorganization following musical training assists basic temporal auditory processes. Conclusions: In general, our results provide a conceptual advance in understanding how musical training influences speech processing, an ability which, when impaired, can affect speech and reading competency.

Audiometria wysokich częstotliwości u pacjentów z szumami usznymi i prawidłowym słuchem. Extended high frequency audiometry in tinnitus patients with normal hearing

Background: Extended high frequency audiometry is not routinely used for diagnostics of tinnitus patients with normal hearing. However, high incidence of high pitch tinnitus in this group of patients naturally inclines to use this diagnostic tool in such cases. Aim of the study: The evaluation of extended high frequency audiometry usefulness in audiological diagnostics of tinnitus patients with normal hearing (0.25–8 kHz). Material and methods: 175 persons with tinnitus and normal audiogram (0.25–8 kHz) and 60 persons in the control group, age up to 40. A high frequency hearing threshold was measured at 10; 12.5, 14 and 16 kHz, by a top-down method. Results: In the unilateral tinnitus group higher values of the hearing threshold for frequencies >8 kHz were observed in ears with tinnitus than in non-tinnitus ears both in the same study group and in comparison with controls. In bilateral tinnitus 17 Prace badawcze

The Influence of High Frequency Hearing Loss on the Distortion Product Otoacoustic Emissions in Tinnitus Subjects with Normal Hearing Thresold (0,25-8kHz)

AIM OF THE STUDYnTo evaluate the influence of high frequency hearing loss (> 8000 Hz) on distortion product otoacoustic emissions registered in the frequency range from 0,5 to 8 kHz.nnnMATERIAL AND METHODSn280 ears with tinnitus and normal hearing (0.25-8 kHz) divided into 3 groups depending on the degree of high frequency hearing loss: group A--hearing threshold up to 20 dB for 10, 12.5, 14 and 16 kHz (68 ears); group B--hearing threshold 25-40 dB HL for at least one of four EHfs (93 ears); group C--hearing threshold above 40 dB HL for at least one of four EHFs (119 ears). For each group mean audiogram and DP-gram were obtained and statistical analysis was used for comparison across these groups.nnnRESULTSnMean DPOAE values in group C were significantly lower in comparison with group A for the frequency range 2-8 kHz, and in comparison with group B were significantly lower for the frequency range 4-8 kHz.nnnCONCLUSIONSnHigh frequency hearing loss (above 8 kHz) has a relevant influence on distortion product otoacoustic emissions registered at frequencies below 8 kHz in tinnitus patients. The greater is hearing loss above 8 kHz, the lower is DPOAE value below 8 kHz.

OTOACOUSTIC EMISSIONS EVOKED BY TWO-TONE BURSTS USING LINEAR AND NON-LINEAR PROTOCOL

Otoacoustic emissions (OAEs) were recorded for tone bursts presented separately and as a two-tone burst complex. Signals were delivered at 70 dB SPL using a non-linear processing method and at 60 dB SPL using a linear method. Two types of stimuli were applied to record tone burst OAEs (TBOAEs): (a) cosine-windowed tone bursts of 5-ms duration with center frequencies of 1, 1.5, 2 and 3 kHz, (b) complex stimuli consisting of a digital addition of the 1-kHz tone burst together with either the 1.5-, 2or 3-kHz tone burst. Recorded signals were processed using the method of adaptive approximations by matching pursuit (MP). The MP method allowed decomposition of signals into waveforms of defined frequency, latency, time span, and amplitude. This approach provided a high time–frequency (t–f) resolution and identified patterns of resonance modes that were characteristic for TBOAEs recorded in each ear. The effect of suppression was statistically significant only for the 1, 1.5-kHz condition and slightly greater for the non-linear mode than for the linear mode. For the dual stimulation by 1 and 1.5-kHz, the MP revealed the existence of closely positioned resonance modes associated with responses recorded individually with the stimuli differing in frequency by 500 Hz. The comparison of t–f distributions calculated for dual (two-tone bursts) and sum-of-singles conditions exhibited mutual suppression of resonance modes common to both stimuli.