Title: Audio equipment testing
Content: of human hearing—20 kHz. Some sources, such as FM radio, will not reproduce frequencies higher than 15 or 16 kHz. Subjectivists claim that experienced listeners can be relied upon for valid advice on how equipment sounds. British Hi-fi critic, Martin Colloms, writes that "the ability to assess sound quality is not a gift, nor is it the feature of a hyperactive imagination; it is simply a learned skill", which can be acquired by example, education and practice. In any event, the eventual purchase decision will be made by the end-user, whose "perception is reality" and can be influenced by factors

Title: Equal-loudness contour
Content: been superseded and incorporated into newer standards. The definitive curves are those defined in the international standard ISO 226:2003, which are based on a review of modern determinations made in various countries. The human auditory system is sensitive to frequencies from about 20 Hz to a maximum of around 20,000 Hz, although the upper hearing limit decreases with age. Within this range, the human ear is most sensitive between 2 and 5 kHz, largely due to the resonance of the ear canal and the transfer function of the ossicles of the middle ear. Fletcher and Munson first measured equal-loudness contours

Title: Audiology and hearing health professionals in developed and developing countries
Content: in the community of rural Bangladeshi village used a simple condition play response procedure (Berg et al., 2006 ). Recommended test frequencies are 1000, 2000, and 4000 Hz, at 20 dB HL according to the ASHA (1997) guidelines for screening audiometry. However, 500 Hz has been found to identify the auditory impact of otitis media with effusion in children and should be included at 25 dB HL when permitted by ambient noise levels (WHO, 1997). In regards to equipment, noise-excluding earphones are advisable in order to limit external noise factors. If possible, though costly, an effective way to reduce background

Title: Audio frequency
Content: Audio frequency An audio frequency (abbreviation: AF) or audible frequency is characterized as a periodic vibration whose frequency is audible to the average human. The SI unit of audio frequency is the hertz (Hz). It is the property of sound that most determines pitch. The generally accepted standard range of audible frequencies for humans is 20 to 20,000 Hz, although the range of frequencies individuals hear is greatly influenced by environmental factors. Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. High frequencies are the first to be affected by

Title: Sound from ultrasound
Content: and Health Administration (OSHA) to increase the exposure limit by an additional 30 dB under some conditions (equivalent to a factor of 1000 in intensity). For frequencies of ultrasound from 25 to 50 kHz, a guideline of 110 dB has been recommended by Canada, Japan, the USSR, and the International Radiation Protection Agency, and 115 dB by Sweden in the late 1970s to early 1980s, but these were primarily based on subjective effects. The more recent OSHA guidelines above are based on ACGIH (American Conference of Governmental Industrial Hygienists) research from 1987. Lawton(2001) reviewed international guidelines for airborne ultrasound in

Question: What is the study and use of frequencies above 20 khz?
Answer: Ultrasonic's