we compared the extent of temporary threshold shift (tts) and hair cell loss following high level 4 khz noise exposure with those preconditioned with moderate level 1 and 4 khz octave band noise. fifteen male albino guinea pigs (300- 350 g in weight) were randomly allocated into three groups: those exposed to 4 khz octave band noise at 102 db spl (group 1, n=5); those conditioned with 1 khz oct...

One of the key requirements for MEMS speakers is to increase sound pressure level (SPL) while keeping size as small possible. In this paper we present a speaker based on piezoelectric bimorph cantilevers that produces higher SPL than conventional unimorph cantilever speakers. The active diaphragm 1.4 × mm2. are connected in parallel make full use actuation voltage. At 1 kHz, measured reached 73...

The central nucleus of the inferior colliculus (IC) is a major integrative center in the central auditory system. It receives information from both the ascending and descending auditory pathways. To determine how single IC neurons integrate information over a wide range of sound frequencies and sound levels, we examined their intracellular responses to frequency-modulated (FM) sounds in awake l...

The Auditory Steady-State Response (ASSR) was recorded in 20 awake adults with normal hearing on ten EEG channels simultaneously to find derivations with the best signal-to-noise ratios (SNRs). Stimuli were 20% frequency modulated tones of 0.5 and 2 kHz at 20 dB SL, 100% amplitude modulated at 90 or 94 Hz, and presented one at a time to one ear. ASSR recordings using a set of at least three cha...

In vitro and in vivo studies have identified that low-frequency ultrasound (US) and microbubbles (MBs) mediate tumor inhibitory effects. However, the application of US in the clinical setting remains unclear. The aim of the present study was to investigate the clinically therapeutic effect of 20 kHz US in combination with MBs for the treatment of hepatic carcinoma. A 71-year-old male with a hep...

Structural, Dielectric and magnetic properties 0.3 CoFe2O4–0.7 BaTiO3–PVDF (polyvinylidene fluride) composite film with different concentration of PVDF: 20, 30 and 40 wt% are reported here for the first time. The structural analysis was carried out using X-Ray diffraction technique, which indicates cubic spinel structure for ferrite phase CoFe2O4 (CFO) and tetragonal structure for ferroelectric...

Grasshoppers of 20 acridid species were examined using spectral analysis, laser vibrometry and electrophysiology to determine whether the song spectra, the best frequencies of tympanal-membrane vibrations and the threshold curves of the tympanal nerves are adapted to one another. The songs of almost all species have a relatively broad-band maximum in the region between 20 and 40 kHz and a narro...

With simple optical geometries a separate resonant Fabry-Perot cavity can serve as an optical feedback element that forces a semiconductor laser automatically to lock its frequency optically to the cavity resonance. This method is used to stabilize laser frequencies and reduce linewidths by a factor of 1000 from 20 MHz to approximately 20 kHz.