Hearing range 60 decibels, the hearing range for the Senegal bushbaby is 92 Hz–65 kHz, and 67 Hz–58 kHz for the ring-tailed lemur. Of 19 primates tested, the Japanese macaque had the widest range, 28 Hz–34.5 kHz, compared with 31 Hz–17.6 kHz for humans. Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than humans or most dogs, detecting frequencies from 55 Hz up to 79 kHz. Cats do not use this ability to hear ultrasound for communication but it is probably important in hunting, since many species of rodents make ultrasonic calls.
2182 kHz produced alternative automatic watchkeeping systems and the 500 kHz band is no longer in use for maritime traffic. In order to operate a marine radio transmitter on 2182 kHz, the operator must hold a GMDSS General Operating Certificate for mandatory installations, a Long Range Certificate for voluntary ones, or other equivalent and recognised radio operator's qualifications. Both these certificates have a wider syllabus than those of the GMDSS Restricted Operators Course or the RYA Short Range Certificate that is necessary for marine VHF use. In practice, an unqualified operator would not be prosecuted for the use of either transmitter in