 Dolby "B" recordings are acceptable when played back on equipment that does not possess a Dolby "B" decoder, such as most inexpensive portable and car cassette players.Without the de-emphasis of the decoder, the sound will be perceived as brighter as high frequencies are emphasized, which can be used to offset "dull" high frequency response in inexpensive equipment.However, Dolby "B" provides less effective noise reduction than Dolby "A", generally by a factor of more than 3 dB.