This study assessed the effects of spectral smearing and temporal fine structure (TFS) degradation on masking release (MR) (the improvement in speech identification in amplitude-modulated compared to steady noise observed for normal-hearing listeners). Syllables and noise stimuli were processed using either a spectral-smearing algorithm or a tone-excited vocoder. The two processing schemes simulated broadening of the auditory filters by factors of 2 and 4. Simulations of the early stages of auditory processing showed that the two schemes produced comparable excitation patterns; however, fundamental frequency (F0) information conveyed by TFS was degraded more severely by the vocoder than by the spectral-smearing algorithm. Both schemes reduced MR but, for each amount of spectral smearing, the vocoder produced a greater reduction in MR than the spectral-smearing algorithm, consistent with the effects of each scheme on F0 representation. Moreover, the effects of spectral smearing on MR produced by the two schemes were different for manner and voicing. Finally, MR data for listeners with moderate hearing loss were well matched by MR data obtained for normal-hearing listeners with vocoded stimuli, suggesting that impaired frequency selectivity alone may not be sufficient to account for the reduced MR observed for hearing-impaired listeners.

No abstract

Patients fitted with the Digisonic® SP implant showed significantly better scores after 3, 6, and 12 months (mean scores: 53%, 62%, and 68% for words; 58%, 69%, and 75% for sentences) than those fitted with the Convex implant (34%, 42%, and 43% for words; 38%, 59%, and 51% for sentences). The improvement in speech perception after implantation for SP patients continued throughout the 12 months for words and 6 months for sentences, versus 6 months for words and 3 months for sentences for Convex patients.

MEIs started to take form in researchers' mind in the 1930s with the first experiment of Wilska. In the 1970s, several devices, such as the Goode and Perkins', the Maniglia's, or the Hough and Dormer's were created but remained prototypes. It is only in the 1990s the devices that emerged remained on the market. In 1994, Symphonix, Inc. was created and aimed to manufacture and commercialize its semi-implantable MEI, the VSB. The principle of the VSB lies on a direct drive of the sound to a vibratory structure of the middle ear through an electromagnetic transducer, the floating mass transducer (FMT). The particularity of the system VSB is the simplicity of the transducer which is made of both the magnet and the coil; thus, the FMT, fixed on a vibrating middle ear structure, mimics the natural movement of the ossicular chain by moving in the same direction. The goal of the VSB was to give an alternative to patients with mild-to-severe sensorineural hearing loss who could not wear hearing aids (HAs) or who were unsatisfied conventional HA users. Subsequent to Tjellström's experiment in 1997, implantations started to include etiologies such as otosclerosis, radical mastoidectomy, failed ossiculoplasty/tympanoplasty, and atresia. Nowadays, the VSB, with more than 20 years of experience, is the oldest and most used middle ear implant worldwide. It is well acknowledged that the straightforward design and reliability of the transducer have certainly contributed to the success of the device.

In this prospective study the outcome of the Digisonic® SP Binaural cochlear implant (CI), a device enabling electric stimulation of both cochleae by a single receiver, was evaluated in 14 postlingually deafened adults after 12 months of use. Speech perception was tested using French disyllabic words in quiet and in speech-shaped noise at +10 dB signal-to-noise ratio. Horizontal sound localization in quiet was tested using pink noise coming from 5 loudspeakers, from –90 to +90° along the azimuth. Speech scores in quiet were 76% (±19.5 SD) in the bilateral condition, 62% (±24 SD) for the better ear alone and 43.5% (±27 SD) for the poorer ear alone. Speech scores in noise were 60% (±27.5 SD), 46% (±28 SD) and 28% (±25 SD), respectively, in the same conditions. Statistical analysis showed a significant advantage of the bilateral use in quiet and in noise (p < 0.05 compared to the better ear). Significant spatial perception benefits such as summation effect (p < 0.05), head shadow effect (p < 0.0001) and squelch effect (p < 0.0005) were noted. Sound localization accuracy improved significantly when using the device in the bilateral condition with an average root mean square of 35°. Compared with published outcomes of usual bilateral cochlear implantation, this device could be a valuable alternative to two CIs. Prospective controlled trials, comparing the Digisonic SP Binaural CI with a standard bilateral cochlear implantation are mandatory to evaluate their respective advantages and cost-effectiveness.