When speaking on the telephone we often run into trouble with particular words that, in face-to-face conversation, aren’t troublesome at all. Words such as “feeling” and “ceiling” seem especially hard to get across the line — or to understand when listening to someone else. Is there a reason for this?.
In fact, there are several reasons, the major one being that telephones completely remove any visual cues from the process of communication. Not only do we read emotional content off the posture of a speaker’s body and face, but language comprehension is aided by a subtle form of lip reading. This has nothing to do with speech or hearing impairments: everyone lip-reads for cues during face-to-face conversation, such as the shape of the lips in producing the “f” sound and not the “s” sound.
A second reason f and s are so troublesome in phone conversation is that they occur at slightly higher frequencies than telephones are built to transmit. That means the phone simply cuts off the high end of the sound you are trying to produce, making it that much harder to distinguish.
In a sense, telephones replicate the hearing loss that comes naturally with age. Older people also experience an increasing inability to distinguish the high end of frequencies, making it harder and harder as the years go by to understand other folks’ words. So there may be a beneficial side to all this: a young person on the phone can get at least some sense of the frustration an older person may experience every day.