Andrzej Wicher

Development of a fast method for determining psychophysical tuning curves

Psychophysical tuning curves (PTCs) can be used to assess the frequency selectivity of the auditory system and to detect and delimit “dead regions” in the cochlea. However, the traditional method for determining PTCs takes too long for use in clinical practice. We evaluated a fast method for determining PTCs, using a band of noise that sweeps in centre frequency and a Békésy method to adjust the masker level required for threshold. The shapes of the PTCs were similar for the fast and traditional methods, for both normally hearing and hearing-impaired subjects. Rates of change of masker level of 2 dB/s or less gave the most reliable results. A relatively wide bandwidth (20 percent of the signal frequency or 320 Hz, whichever is the smaller) was needed to minimise the influence of beat detection. When the signal frequency fell within a dead region, the fast method gave PTCs with shifted tips.

Polish sentence tests for measuring the intelligibility of speech in interfering noise

The aim of this study was to develop Polish sentence tests for accurate measuring of speech intelligibility in masking interfering noise. Two sets of sentence lists have been developed. The first set was composed of 25 lists and was used for sentence intelligibility scoring. The second set was composed of 22 lists and was used for word intelligibility scoring. The lists in each set have been phonemically and statistically balanced. The speech reception threshold (SRT) and slope of the psychometric function at the SRT point (S50) were determined in normal-hearing subjects. It was found that the mean SRT and mean list-specific S50list for the first set were equal to −6.1 dB and 25.5%/dB, respectively. The mean SRT and the mean list-specific S50list for the second set were:−7.5 dB and 20.8%/dB. Due to a relatively steep slope of the psychometric functions, the Polish sentence tests were shown to be accurate materials for speech intelligibility measurements against interfering noise. They are the first sentence speech-in-noise tests developed for Slavonic languages.

Effect of broadband and narrowband contralateral noise on psychophysical tuning curves and otoacoustic emissions

The relative effectiveness of narrowband and broadband noises in activating the efferent system was assessed by comparing the effect of contralateral stimulation (CS) with such sounds on psychophysical tuning curves (PTCs) determined in simultaneous masking, using signal frequencies of 1000 or 2000 Hz. To check that the CS stimuli used did activate the efferent system, distortion product otoacoustic emissions (DPOAEs) were also measured in the absence and presence of narrowband and broadband CS. The CS had no consistent effect on the masker level at the tips of the PTCs. A broadband pink noise CS consistently reduced the masker level required for threshold on both the low- and high-frequency sides of the PTCs for the 2000-Hz signal frequency. However, there were no consistent effects of the CS for any other case. The broadband pink noise CS had a greater effect in reducing DPOAE levels than the narrowband CS. The results provide psychophysical evidence supporting the idea that the efferent system is activated more effectively by a broadband than by a narrowband CS, at least for a signal frequency of 2000 Hz.

The Influence of a Single Therapeutic Dose of Methadone on Selected Auditory Functions in Patients Addicted to Opioids and Undergoing Substitution Therapy – a Preliminary Study

The main purpose of this research was to determine the influence of a therapeutic dose of an opioid drug (methadone) on selected auditory functions in patients addicted to opioids (recognition ICD-10; F11) and undergoing substitution therapy. Various hearing tests were used in this research – pure tone audiometry, impedance audiometry, otoacoustic emission measurement, and a speech in noise test – in two sessions, before and after methadone intake. It was found that methadone causes an improvement in speech intelligibility when speech is presented in speech-like noise, and slightly decreases hearing thresholds [dB HL]. Methadone consumption has no significant impact on distortion product otoacoustic emissions levels (DPOAE). In summary, a prescribed methadone dose does not worsen the hearing of opioid-dependent subjects.

2890 – Speech understanding and logatom intelligibility in alcohol addicts during detoxification in hospital

Objectives The aim of research is to assess a speech perception in alcohol addicts and healthy ones. Methods 65 alcohol addicts (mean age 38 years, min. 22, max. 66 years) were examined. Patients admitted hearing impaired were excluded. The average duration of addiction: 8.8 years. The measure of speech understanding is the ratio of correctly received phonetic elements to the total number of presented ones. Speech understanding is often determined in the presence of masking noise. Respondents are to arrangement of sentences with words heard in the noise. The test determines the intensity of speech, for which - if it is presented in the noise - observed in 50% of correct answers. This parameter is called the Threshold Reception Speech (SRT). The logatom intelligibility test consists with over 150 presented stimuli. Both tests were conducted in a soundproof booth Results In the speech understanding test were found significant difference of average SRT between alcohol addict and healthy ones. The better understanding of speech was found in healthy individuals. In a study conducted in the final phase of detoxification treatment, it was found that the level of speech understanding in addicts was improved (statistically significant). In the logatom intelligibility test wasn’t differences. Conclusions It was found that alcohol dependence is associated with worse perception of speech.

Effect of broadband contralateral noise on distortion product otoacoustic emissions and psychophysical tuning curves

The main purpose of this work was to describe an influence of contralateral stimulation (CS) on distortion products otoacoustic emissions (DPOAEs) and psychophysical tuning curves (PTCs). The fast method for determining PTCs was used in the study. DPOAEs and PTCs were measured in two modes: in the presence or absence of CS. The CS was a broadband noise at a level of 50 SPL. The primary tones with frequencies f1 and f2, (f2/f1 = 1.21) were presented at levels of L1 = 60 dB SPL, and L2 = 50 dB SPL. A pulsed sinusoidal signal at a sensation level (SL) of 10 dB was used in the measurements of the PTC. The signal frequency was 1 or 2 kHz. Ten normal-hearing subjects participated in this study. The CS caused a decrease in the level of the DPOAEs (suppression effect) in 90% of cases, in the whole frequency range of f2 (i.e. from 845 to 6200 Hz). The maximum suppression of the DPOAE level occurs for the f2 frequency from 1 to 2 kHz. For both signal frequencies the CS significantly reduces the sharpness of the PTC...