Antoni Grzanka

Identification of otoacoustic emissions components by means of adaptive approximations.

Clicks and a set of tone bursts covering the same frequency band were applied as a stimuli evoking otoacoustic emissions (OAE). Recorded otoacoustic emissions were decomposed into the basic waveforms by means of high-resolution adaptive time-frequency approximation method based on the matching pursuit algorithm. The method allows for description of the signal components in terms of frequencies, time occurrences, time spans, and energy. The analysis of OAEs energy density distributions in time-frequency space revealed that click responses can be considered as linear superpositions of responses to tone bursts, The frequency-latency relationship was studied and compared with earlier works. The method made possible the exhaustive description of the resonant modes specific for given subject/ear. They were characterized not only by the close frequencies appearing for different tones, but they usually had similar latencies and time spans. Short-time and long-time resonant modes were identified. The second ones might be connected with spontaneous emissions. The method opens new perspectives in studying the fine structure of the OAE and testing of the theoretical models.

Effects of impulse noise on transiently evoked otoacoustic emission in soldiers Efectos del ruido impulsivo sobre las emisiones otoacústicas evocadas por transitorios en soldados

The aim of the study was to assess the effects of exposure to impulse noise on TEOAE, as compared to PTA. The study comprised 92 soldiers, subjected to impulse noise during military service. The control group consisted of secondary school students, not exposed to noise. Extended high frequency PTA, and TEOAE were recorded before and after one year of military service. The total level of noise and spectrum analysis were performed for all kinds of weapons, separately. The highest levels of noise for weapons were related to frequencies from 1.6–16 kHz. After military service significant deterioration of hearing was observed on average by 6 dB exclusively at the frequencies of 10 and 12 kHz. TEOAE reduction was registered predominantly at frequencies of 2, 3 and 4 kHz, with the greatest decrease at 2 kHz (p<0.02). The control group did not show any significant audiometric changes as well as TEOAE during the time of experiment.

Changes in nasal cavity dimensions in children and adults by gender and age.

Objective: The aim of the study was to establish the dynamics of changes in the intranasal spaces of children and adults by gender and age.

Time-Frequency Analyses of TEOAE Recordings from Normals and SNHL Patients

This study evaluated the characteristics of transient evoked otoacoustic emission (TEOAE) time-frequency (TF) representations from normal and hearing-impaired ears. Linear and non-linear TEOAE recordings from normally-hearing subjects (40) and non-linear recordings from patients with sensorineural hearing loss (SNHL) (40) were analysed using the short-time-Fourier-transform spectrogram, the Gabor spectrogram, and the adaptive spectrogram. The TF representations of the TEOAE recordings indicated a considerable dispersion of energy across frequencies and TEOAE time segments × 4.0 ms. The linear and non-linear recordings from the normal subjects showed common frequency peaks. The TF representations from the patients with SNHL indicated that the significantly reduced energy in the mid-to-high TEOAE frequencies did not correlate closely with the threshold elevation. As in the recordings from the normal subjects, a high percentage of the TEOAE cumulative energy was found within a short TEOAE segment (4-14 ms).

Bilateral nasal allergen provocation monitored with acoustic rhinometry. Assessment of both nasal passages and the side reacting with greater congestion: relation to the nasal cycle

Background The effect of bilateral nasal provocation on nasal mucosa measured with the use of acoustic rhinometry (AR) can be assessed for both nasal passages or for the side responding with greater congestion. Assessment of changes in nasal congestion during the nasal provocation test (NPT) can be affected by the nasal cycle (NC). The aim of this study was to find out the most accurate method to evaluate changes observed during bilateral nasal provocation.

Comparison of Neonatal Transient Evoked Otoacoustic Emission Responses Recorded with Linear and QuickScreen Protocols

Linear and QuickScreen (non-linear) transient evoked otoacoustic emission (TEOAE) protocols were compared in terms of standardized clinical parameters in order to define the protocol producing recordings with the highest signal quality. Neonatal responses (520) were obtained from three different screening sites. The linear recordings were evoked by 69 and 75-dB p.e. SPL clicks. All responses were post-windowed by a 3.5- to 12.5-ms window, chosen by time-frequency analysis as the segment representing 97.35 per cent (linear) and 95.6 per cent (quick) of the total cumulative spectral energy. Evidence from hearing loss cases and the high similarity between the profile contours of the QuickScreen and the linear normal recordings have strongly suggested that a linear response evoked by a 75-dB p.e. SPL stimulus and post-processed by a 3.5 to 12.5 window is free of stimulus artefacts. The data indicate that the 75-dB linear protocol produces higher signal to noise ratios at 2.0, 3.0, and 4.0 kHz, higher wave reproducibility, and lower TEOAE noise values than the QuickScreen protocol.

Methods for formant extraction in speech of patients after total laryngectomy

Abstract The paper shows the methods and its application for voice analysis suited to the group of subjects after total laryngectomy surgery. Our software was developed to evaluate and enhance laryngectomized patients’ rehabilitation process. The power spectral density imaging and formant frequencies extraction methods were adopted. The model of vocal tract was based on statistical, autoregressive process of speech production. The transversal filter and adaptive algorithm were implemented to estimate the transfer function of resonance cavities. The research is concerned with measurements of vowel articulation parameters, especially F1 and F2 formant frequencies. The significant difference of pathological and normal voice in vowel space separation has been presented. The authors found that formants in pseudowhisper speech are more pronounced while articulating vowel after consonant than for sustained vowel.

Optimization of TEOAE recording protocols: A linear protocol derived from parameters of a time-frequency analysis: a pilot study on neonatal subjects

Linear and non-linear TEOAE protocols were compared in terms of nine parameters in order to define the protocol producing recordings with the highest signal quality (lowest noise and highest signal-to-noise ratio). The pilot project acquired data using ILO-92 apparatus from 220 neonates (397 ears) at the second/third day after birth in three European laboratories. A Gabor spectrogram time-frequency representation of the recordings showed considerable frequency dispersion in TEOAE latencies >4.0 ms. The data, analysed with a Wilcoxon test, indicated that a linear TEOAE protocol: (i) generates recordings of a lower noise and a higher signal-to-noise (S/N) ratio in the 2.0, 3.0, 4.0 kHz TEOAE bands; (ii) the increase in the S/N ratio can result in a decrement of the required number of TEOAE sweeps; (iii) the higher values of S/N can be used in the estimation of more robust pass-fail criteria, minimizing the percentage of false positives and negatives.

Correlations between risk factors for hearing impairment and TEOAE screening test outcome in neonates at risk for hearing loss.

The aim of the study was to find the correlation between specific risk factors for hearing impairment as well as between risk factors and TEOAE screening results in neonates at risk for hearing impairment. Seventy-one newborns at risk for hearing impairment have been included in the study. Strong correlations between specific risk factors were found. Investigation of the relationship between specific risk factors and TEOAE signal-to-noise ratio (SNR) showed that in children with genetic risk factors, TORCH (toxoplasmosis, rubella, CMV, herpes virus, others) infections and in those treated with ototoxic drugs, the values of SNRs were significantly lower than in children at risk who did not present those factors. In case of hyperbilirubinaemic children the values of SNR were significantly higher than in the controls. In our opinion these relationships may be partially explained by the positive predictive values of these risk factors, but other intrinsic factors may also be involved.

A FOUR CHANNELS ELECTROHYSTEROGRAPH WITH INDIVIDUALLY SELF TUNING AMPLIFIER GAINS

The paper presents the specialized measurement system aimed on reliable recording of electrohysterographical (EHG) signals in pregnant women. System offers efficient attenuation of the mains interference and DC offset, together with adjustable gain, allowing to suit its sensitivity to the level of signal available in the particular patient. The noise level is further reduced by optimized bandwidth and optical fiber based connection between the EHG device and recording computer.