Biomedical subjects

John P Preece

Publications and source records attributed to John P Preece.

3 recordsLinked to original sources

PubMed2002

Three-month results with bilateral cochlear implants.

OBJECTIVES: To evaluate possible binaural listening advantages for speech in quiet, speech in noise, and for localization in a group of postlingually deafened adults with two cochlear implants functioning independently after 3 mo experience. DESIGN: Nine postlingually deafened subjects who had received a Cochlear Corporation CI24M implant in each ear were evaluated on a number of tasks. The subjects all had audiometric or biographical (e.g., duration of deafness) differences between the ears. Word and sentence materials were presented to the subjects in quiet and in noise with the signal always in the front and the noise from the front or either side. Results are reported for each ear and for both ears with the noise on either side. This allowed evaluation of head shadow and squelch effects. Additionally, localization ability was assessed for broadband noise presented either to the right or left of center at 45 degrees azimuth. Localization was assessed for each ear and for both ears. RESULTS: Results of speech testing in quiet showed a significant advantage for the binaural condition over the better ear in four subjects. In noise, with both signal and noise in front of the subject, a significant advantage of two ears over the better ear was found for four subjects. For noise to one side of the head, when the ear opposite the noise source was added to the ear ipsilateral to the noise, a significant advantage was demonstrated for seven of seven tested subjects. When the ear ipsilateral to the noise was added to the ear contralateral to the noise, a significant advantage was shown for only one of seven (noise on right) and three of seven (noise on left) tested subjects. The localization task showed that all seven tested subjects could discriminate 45 degrees left from 45 degrees right above chance with bilateral stimulation. Three subjects could perform the discrimination above chance with only one ear. However, performance with both ears was significantly better than performance with one ear for two of these latter subjects. CONCLUSIONS: We conclude that bilateral cochlear implants can provide real advantages, particularly when it is possible to utilize the ear that is away from a noise source, thus taking advantage of the head shadow effect. In addition, localization ability was generally better with two implants than with one.

Acoustic Stimulation↗

PubMed2002

Patients utilizing a hearing aid and a cochlear implant: speech perception and localization.

OBJECTIVE: The purpose of this pilot study was to document speech perception and localization abilities in patients who use a cochlear implant in one ear and a hearing aid in the other ear. DESIGN: We surveyed a group of 111 cochlear implant patients and asked them whether they used a hearing aid on their unimplanted ear. The first three patients who were available were tested on word and sentence recognition and localization tasks. Speech stimuli were presented from the front in quiet and in noise. In the latter conditions, noise was either from the front, the right, or the left. Localization was tested with noise bursts presented at 45 degrees from the right or left. In addition we asked the patients about their abilities to integrate the information from both devices. RESULTS: Speech perception tests in quiet showed a binaural advantage for only one of the three patients for words and none for sentences. With speech and noise both in front of the patient, two patients performed better with both devices than with either device alone. With speech in front and noise on the hearing aid side, no binaural advantage was seen, but with noise on the cochlear implant side, one patient showed a binaural advantage. Localization ability improved with both devices for two patients. The third patient had above-chance localization ability with his implant alone. CONCLUSIONS: A cochlear implant in one ear and a hearing aid in the other ear can provide binaural advantages. The patient who did not show a clear binaural advantage had the poorest hearing aid alone performance. The absolute and relative levels of performance at each ear are likely to influence the potential for binaural integration.

Cochlear Implants↗

PubMed2002

Binaural cochlear implants placed during the same operation.

OBJECTIVE: To evaluate the binaural listening advantages for speech in quiet and in noise and to localize sound when independently programmed binaural cochlear implants are used, and to determine whether ears with different hearing ability and duration of profound deafness perform differently with cochlear implants as well as to what extent preimplant psychophysical and physiologic assessment could be predictive of performance. STUDY DESIGN: Prospective study in which patients were prospectively selected to undergo bilateral implantation during a single surgical procedure at a tertiary referral center. All testing was performed with patients using their right, left, or both cochlear implants. Preimplant and intraoperative measures used electrical stimulation at the round window and stimulation through the cochlear implant. RESULTS: Bilateral implantation during the same operation did not cause any postoperative problems such as severe vertigo or ataxia. At 1 year, results of speech testing in quiet demonstrated a binaural advantage for 2 of 10 subjects. Speech-in-noise testing demonstrated that two implants were beneficial for two individuals. All subjects benefited from a head shadow effect when an ear with a better signal-to-noise ratio was available. The ability to localize sound was improved with binaural implants in all subjects. Preimplant psychophysical or physiologic measures were not predictive of eventual speech perception performance. CONCLUSION: Binaural cochlear implants can assist in the localization of sounds and have the potential in some individuals to improve speech understanding in quiet and in noise.

Adult↗