FeONIC® Audio Drives work in a totally different way from speakers.

Unlike speakers, FeONIC® Audio Drives are solid state and have no moving parts. They do not wear or deteriorate and can survive temperatures in excess of 150ºC.

A FeONIC® Audio Drive uses the structure of buildings, platforms, platform screen doors, waiting rooms, panelling (in fact, any resonant surface such as such as glass, metal, wood or plastic) to transform the surface of the material into a fantastic speaker without design aesthetic or audio compromise.

The Audio Drive can be discreetly attached to the front or rear of any suitable surface and, when an audio signal is delivered to it, the entire surface of the substrate on which the Audio Drive is mounted becomes the speaker. The sound created is omni-directional and the audio output from the substrate material evenly distributed. The frequency response of the output is not significantly affected by the position of the listener relative to the position of the FeONIC® Audio Drive.

Therefore, it is less likely that valuable speech information (intelligibility) is lost through change in frequency response or SPL, as it is with speakers.

With the most effective resonant surfaces, such as rigid honeycomb aluminium panels, the sound generated by a FeONIC® Audio Drive can travel a long distance through the length of the panel with negligible loss of volume across the entire length and breadth. By comparison the attenuation in air for loudspeakers is 3dB loss for every metre away from the speaker.

Similarly, FeONIC® Audio Drives can be driven at a lower volume (SPL) than a speaker, yet deliver an audio signal over a wider area. Speakers tend to be driven at high SPL levels in an attempt to cover large areas, but this result in uneven sound distribution and poorer sound quality.

The Speech Intelligibility Index (SII) is a measure of the intelligibility of speech. The FeONIC® Audio Drive regularly achieves an SII greater than traditional loudspeakers, making it by far the best system to install.

The Speech Intelligibility Index is the amount of speech that is recognised correctly, on a scale of 0 to 1, where 1 is excellent and 0.5 is fair to good. In most PA applications an SII value of 0.5 or above is acceptable and FeONIC® Audio Drives regularly deliver over 0.6 SII without distortion and with a more even distribution of sound than speakers.

Intelligible announcements in a transport environment are essential to ensure passenger safety, information and satisfaction. Traditional speaker-based systems don’t live up these requirements, because they lack speech intelligibility which measures the quality of sound on four key measures:

• Speech-signal-to-noise ratio (S/N). Noise has the effect of masking or obscuring the voice signal. Remarkably, we are able to tolerate a great deal of noise before intelligibility diminishes appreciably but, once it begins to diminish, it diminishes rapidly.
• Reverberation. Most people are familiar with how difficult it can be to understand speech in a reverberant environment such as a railway station or airport. Reverberation is made up of sound reflections that have the effect of smearing or blurring speech, making it less clear and distinct and therefore more difficult to understand.
• Echoes. If echoes arrive much later in time than the first arrival of sound, they can harm intelligibility. In continuous speech, the echo from a previously uttered syllable masks or obscures the sound of subsequent syllables, making speech more difficult to understand. The time delay and level of the echo are key variables in determining the impact of echoes on intelligibility.
• Distortion. If one of the electrical or electro-acoustical components in the sound system is distorting, it is generating a form of noise that masks the original speech signal. Severe amplifier clipping, for example, can make an otherwise perfect speech signal at the input to the amplifier more difficult to understand at the output.

Speech is not necessarily intelligible simply because it is audible. Having enough speech level is a necessary, but not sufficient, condition for good intelligibility. Just like adding more light to a blurry text doesn’t make it more legible, adding more sound level to speech that has been blurred by reverberation, echoes or distortion does not make it more intelligible. A loud enough, but overly reverberant, speech signal can be almost completely unintelligible, to which users of many railway stations and airports can easily attest. FeONIC®'s Audio Drive technology overcomes these problems, providing superior levels of speech intelligibility.

Voice alarms are a good example of the importance of speech intelligibility. Voice alarm systems are meant to inform and instruct building occupants in the event of an emergency and their use is based on strong evidence that people often ignore normal audible and visual alarms but will obey a voice command, and that normal alarms have extremely limited information content (on or off), whereas voice can be used to deliver a wide range of potentially life-saving information. However, for a voice alarm system to be effective, it must be intelligible. FeONIC’s Audio Drive technology ensures that it will be much more intelligible than traditional speaker systems – potentially saving lives.