Nonsense-syllable recognition in noise using monaural and binaural listening strategies.

Using a binaurally equipped KEMAR manikin, syllables of the CUNY Nonsense Syllable Test were recorded in sound field at 0-degree azimuth against a background of cafeteria noise at 270-degrees azimuth, at several signal-to-noise (S/N) ratios. The combination of inputs recorded at each ear was delivered to ten normal-hearing (NH) and eight sensorineurally hearing impaired (HI) listeners through insert ear phones to produce five experimental listening conditions: (1) binaural head shadow (HS), in which ear presentation was analogous to the original stimulus recording, (2) binaural favorable (BF), in which the noise-shadowed (right-ear) recording was presented to both ears, (3) monaural favorable (MF), in which the noise-shadowed recording was presented only to the right ear, (4) monoaural unfavorable (MU), in which the noise-unshadowed (left ear) recording was presented only to the left ear, and (5) simulated monoaural aided (SMA), in which the noise-shadowed recording was presented to the right ear and the noise-unshadowed recording--attenuated by 20 dB relative to the HS condition--was presented to the left ear. All main effects (subject type, listening condition, and S/N ratio) were statistically significant. Normal listeners showed 3.3- and 3.2-dB advantages, respectively, due to head-shadow and binaural squelch, over hearing-impaired listeners. Some hearing-impaired listeners performed better under the SMA or BF conditions than under the HS condition. Potential digital signal processing strategies designed to optimize speech understanding under binaurally aided listening conditions are discussed.

Investigation of endolymphatic hydrops by electrocochleography in patients with Cogan's syndrome.

We compared auditory and vestibular function between a patient with typical Cogan's syndrome and a patient with atypical Cogan's syndrome. Repeat audiograms demonstrated fluctuating sensorineural hearing loss in the affected ear. Brainstem auditory evoked response testing revealed no abnormalities. Hallpike caloric testing showed a decreased response in the affected ear in the typical case and responses within normal limits in the atypical case. Sinusoidal harmonic acceleration was normal in the typical case, and there was an abnormal phase at 0.01 Hz in the atypical case. Endolymphatic hydrops was investigated by electrocochleography. In both patients, there was an enhancement of the summating potential, with an increased ratio of summating potential to action potential amplitude. This finding is consistent with endolymphatic hydrops.

BAER, EOG, MRI and 3-D MR angiography correlates in a case of Locked-In syndrome.

A case of Locked-in syndrome is reported with correlation of BAER and EOG with MRI for localization and identification of brain lesions, and 3-D MRA and 2-D gradient echo MR imaging, a non-invasive new diagnostic modality for confirmation and visualization of vascular pathology. There was thrombosis of the basilar artery with extensive infarct of ventral pons and lower mid-brain. The patient had ocular bobbing. This eye movement in its classical form consists of irregular vertical oscillations, the fast component being downward with complete absence of horizontal eye movements. To our knowledge, the change from ocular bobbing to upbeat nystagmus has not been previously reported in the Locked-in syndrome. Bilateral involvement of the lateral lemniscus might have contributed to its appearance in our patient.

Electrocochleography: a method for making the Stypulkowski-Staller electrode and testing technique.

A method for making the Stypulkowski-Staller tympanic membrane electrode is described step by step. Our testing technique with inserted earphones utilizing click stimulus is reported.

Evidence of central vestibulo-auditory dysfunction in atypical Cogan's syndrome: a case report.

Auditory and vestibular functions were investigated in a patient with atypical Cogan's Syndrome. The brainstem auditory evoked response revealed bilateral severe distortion of morphology and voltage diminution after potential I, greater in right ear recordings. Interwave latency I-III was increased bilaterally. Electronystagmographic studies showed nonfatigable direction changing positional nystagmus greater with right ear undermost and bilateral failure of optic suppression. Findings suggested bilateral pontocerebellar dysfunction. Correlation was found with the side of greater clinical manifestations. The patient had excellent recovery of auditory and vestibular functions with administration of corticosteroids within 2 weeks of the onset of hearing impairment. She was followed up with auditory and vestibular studies for 30 months.

Brainstem auditory evoked response sensitivity: comparison with other neurologic tests in the detection of retrocochlear lesions.

Brainstem auditory evoked response (BAER) tests were obtained in 3 patients with suspected retrocochlear lesions. Subsequently, CT scans and the surgical procedure demonstrated tumors of about the same size (2 cm) in the cerebellopontine angle. One was an VIIIth-nerve schwannoma, one a meningioma, and one a VIIth-nerve neuroma. BAER recordings were analyzed with results of other tests: conventional audiometry, stapedius reflex measurements and electronystagmography (ENG). A striking finding was a normal BAER in the patient with the VIIIth-nerve schwannoma. ENG recordings in this case showed ipsilateral impairment of optokinetic nystagmus. The BAER was abnormal in the other 2 patients. A consistent abnormality for the 3 patients was absence of stapedius reflex in the ear in question. This study disclosed the advantage of utilizing a battery of tests in the investigation of retrocochlear lesions. The ENG recordings should include evaluation of the vestibulo-oculomotor pathways.