Speaker systems have utilized low frequency (bass), mid-range frequency, and high frequency (tweeter) speakers to provide a wide operating frequency range required to reproduce audio program material having a very wide frequency range. Such speaker systems have often relied on cross-over networks to separate audio program material into low frequency, mid frequency and high frequency components for optimum reproduction by the bass, mid-range, and high frequency speakers. Such cross-over networks are often complex and add to the expense of the speaker system.
Headphones are often relied upon to provide listening capability for portable radio frequency receivers. Piezoelectric transducers have often been used in such headphones to provide the frequency response necessary to present the audio program material. As a result, there is no provision to handle separately the low frequency, mid frequency and high frequency components of the audio program material, which often leads to a less than optimum wide frequency response from the headphones.
What is therefore needed is a transducer which can provide a low frequency response, and which can be coupled to other transducers which have mid range and high frequency responses without the need for crossover networks to provide a wide operating frequency range.