1 M or m â prefix designating a number in thousands (not to be confused with SI prefix M for mega-or m for milli).
There are two types commonly referred to as: 'Shallow' and 'Deep' water. The differences are not only in the Frequency but also in the Beam Width and they are as follows: 'Shallow' water HST-WSBL 106-72 Transducer will operate on 2 frequencies on the HDS models: 200 (20Â°) & 83KHz (60Â°). 'Deep' water HST-DFSBL 106-77 Transducer will operate on 2 frequencies on the HDS models: 200KHz (12Â°) & 50KHz (35Â°).
High frequency sounds are usually shrill like a whistle whereas low frequency sounds are more like the deep hum of an amplified bass instrument. The highest frequency that most humans can hear is 20,000 cycles per second or 20,000 Hz. This limit gets lower as humans age. Older people generally donât have as large of a hearing range as younger people.