Pitch matching in bimodal cochlear implant patients: Effects of frequency, spectral envelope, and level

Abstract

This study systematically investigated the effects of frequency, level, and spectral envelope on pitch matching in twelve bimodal cochlear implant (CI) users. The participants were asked to vary the frequency and level of a pure or complex tone (adjustable sounds) presented in the non-implanted ear to match the pitch and loudness of different reference stimuli presented to the implanted ear. Three reference sounds were used: single electrode pulse trains, pure tones, and piano notes. The data showed a significant effect of the frequency and complexity of the reference sounds. No significant effect of the level of the reference sounds was found. The magnitude of effect of frequency was compressed in the implanted ear: on average a difference of seven semitones in the non-implanted ear induced the same pitch change as a difference of 19 to 24 semitones for a stimulus presented to the implanted ear. The spectral envelope of the adjustable sound presented to the non-implanted ear also had a significant effect. The matched frequencies were higher by an average of six semitones for the pure tone compared to a complex tone. Overall, the CI listeners might have matched the stimuli based on timbre characteristics such as brightness.

Pitch Matching in Cochlear Implant Users With Single-Sided Deafness: Effects of Electrode Position and Acoustic Stimulus Type

“…This conclusion, however, is not supported by the pitch matches using NBN or PSHC. Another recent study reported an effect of acoustic stimulus type on electric-acoustic pitch matching; Maarefvand et al (2017) have used sinusoids and harmonic complex tones consisting of the first 11 harmonics passed through a bandpass filter with relatively shallow slopes and centered at a frequency equal to 1.6 times the fundamental frequency. The spectral shape of this stimulus was chosen based on the results of a study on timbre by Lazard et al (2012).…”

“…A wide range of methods have been used in the literature to compare the pitches of electric and acoustic stimuli. These include magnitude estimation (Vermeire et al, 2008; Plant et al, 2014), the method of constant stimuli (Boex et al, 2006; Reiss et al, 2007, 2015; Goupell et al, 2019), the method of adjustment (Green et al, 2012; Rader et al, 2016; Maarefvand et al, 2017; Tan et al, 2017) and various kinds of adaptive forced-choice procedures (Reiss et al, 2007; Schatzer et al, 2014; Vermeire et al, 2015; Peters et al, 2016). Carlyon et al (2010) tested several of these methods and showed they could all be potentially contaminated by different kinds of non-sensory biases.…”

“…Their results were very variable, but they found in one subject that the matched frequency was significantly different when using acoustic pulse trains than for sinusoids and noise bands. Maarefvand et al (2017) have used sinusoids as well as harmonic complex tones and found that the pitch-matched frequency for each electrode was always higher when using a pure tone than the harmonic complex tone. Thus far, there is only limited evidence that the choice of acoustic stimulus type can have an effect on the electric-acoustic pitch matching results.…”

Development and Characterization of a Biomimetic Totally Implantable Artificial Basilar Membrane System

“…We analyzed and compared the electrical output of the entire ABM system (ABM + EM + electrode), ABM system with umbo connection, and conventional CI according to the sound pressure (Figure 6B). As shown in Figure 6B, the efficacy of the entire ABM system is lesser by 42.8 dB (approximately 100 times) compared to generating an electrical signal of 1.5 mA at a sound pressure of 74 dB SPL on conventional CI electrodes (Maarefvand et al, 2017). Thus, the electrical output should be approximately 10 2 -fold higher than the output of the present ABM system for effective stimulation of auditory primary neurons when electrodes are placed in the scala tympani compared to conventional CIs.…”

The sound sensation of a pure tone in cochlear implant recipients with single-sided deafness

“…The 250 Hz pure tone (es20) activated the most apical electrode only (electrode 20), while the 1050 Hz pure tone (es14) activated electrode 14 and 13. Such tasks have been performed in previous studies [7], [8], [17][18][19][20][21][22]. However, in these studies, the pulse rate was set to a level either below 40 or above 700 pps in order to minimize the temporal pitch cues.…”