Audio-frequency range

These are meant to be used with a capacitor to tune a filter circuit, with resonances in the audio frequency range for reducing and filtering the harmonics or communication frequencies. They provide a near short-circuit for the required harmonics to filter them out of circuit. They may be single-phase or three-phase and connected in series or parallel of the capacitor circuit and may have a fixed or variable reactance, rated continuously with saturated magnetic characteristics. They may incur heavy losses. 

For polyelectrolyte NaPSS samples, significant nonlinear effects and significant dispersion effects in audio frequency range were recorded quantitatively. Figures 5 and 6 summarize these results. Qualitative behaviors of these phenomena are also summarized at the end of the Results section. These phenomena were not observed significantly in saline solutions as shown in Figure 8. 

The components of a TS system are shown in Figure 11.39 (130). A resonance stethoscope is used to transmit crystalline vibrations in the sample to the audio frequency range where they are converted to electrical signals by use of a piezo-electric crystal. The stethoscope is constructed of quartz, which, because of its high Q value, operates mechanically both as a tuned pick-up sensor and as a self-exciting resonator. The unit incorporates a sample-holder head shaped as an acoustic transformer and fitted with a transmitter rod that mechanically matches the piezo-electric cell fixed on a heavy recoil... 

We can learn more from this analogy between radio systems and NMR spectrometers. In radio, the desired information in the audio frequency range is combined with the carrier wave which is in the rf range. This process of combining the lower frequency information with the carrier is called modulation. The modulated carrier wave is sent out... 

In the past, impedance measurements using reactively substituted Wheatstone bridges at audio frequencies have been the easiest to accomplish. Consequently, great emphasis has been placed historically on electrochemical processes having characteristic impedance spectra in the audio frequency range 20-20,000 Hz, namely, double-layer capacitive and moderately fast reaction kinetic effects at plane parallel electrodes. 

Acoustic refers to a periodic pressure wave. The term is synon5unous with sonic and includes waves in the audio frequency range (ie, those that can be heard by the human ear) as well as those above the audio range ultrasonic and hypersonic) and below the audio range. Acoustic measurement is a form of dsuiamic mechanical measurement, though sometimes the latter term is reserved for low frequency (see also Dynamic Mechanical Properties). 

TABLE 4.72 Center and Approximate Frequency Limits for the Standard Set of Contiguous Octave Bands Covering the Audio Frequency Range... 

The converse piezoelectric effect, when electric field induces mechanical deformation, has special importance because of its influence on the electro-optical responses they are mainly imwanted since they result in misalignment, but with clever design can be used to re-heal alignment. It is interesting to note that in the audio frequency ranges, the vibrations result in audible acoustic effects, implying their possible use in electromechanical transducers. ... 

The ac conductivity of SC2O3 has been measured by Pike (1972) in the audio-frequency range at temperatures between 4 and 295 K. The results are explained in terms of a new hopping model. 

---