In the article you will learn:
- what is the basis of good speech reproduction,
- which parameter has the greatest influence on the good intelligibility of the reproduced voice,
- which other features affect the quality of speech reproduction and the long life of the speaker.
Visaton is without any doubt a top manufacturer of speakers for all segments - from high-end through Hi-Fi to miniature SMD, laptops etc. Their portfolio has solutions for virtually every area. Martin Brestovič, product manager of SOS electronic, talks about the most interesting group of speakers for industrial equipment, as well as the types suitable especially for the reproduction of human speech.
Today, it is quite common for devices to have various messages stored in their memory and, in addition to the optical output on the display or LED and the like, they also give alerts in the form of sound. Typical segments of the use of these loudspeakers are, for example, means of transport, kiosks, medical facilities, parking machines or various systems for voice communication.
What is the essence of good speech reproduction?
The answer is simple. First and foremost, the speaker must have good reproduction in the human voice frequency band. We can find many graphs and tables with the average spectrum of voices in the professional literature, and although the individual sources in the data differ slightly from each other, we can state that "everything essential" is between frequencies from 350 - 400 Hz to about 4 kHz. With extra high precision from approx. 200 Hz to 5 - 6 kHz.
This is pretty good news, because if you pay just a little attention to the speakers, you probably know that this frequency range can easily be covered by one speaker, and even many small and cheap types can easily cover it.
Which parameter has the greatest impact on the good intelligibility of the reproduced voice?
There is yet another parameter that is very important for the voice to sound really true and have a natural color. It is important that the speaker has the most balanced frequency response (sensitivity) in a given frequency band. This is a slightly higher requirement, and the result of a very unbalanced frequency response can be, for example, a typical "metallic" voice coloring and the like.
Equally "rumbling", not very understandable sound is typical of speakers (or more precisely reproduction systems from source to speaker), which emphasize the low tones too much and neglect the higher ones.
The following picture shows two different speakers that should serve as an example of a suitable and less suitable frequency response:
We will now intentionally omit applications where there are large areas and the intelligibility is affected by the echo and also the directional pattern of the speakers. We focus only on "small" applications, where the speaker that is used plays a key role in intelligibility.
What are the other features that also affect the quality of speech reproduction and the longevity of the speaker in the application?
In most cases, a speaker with a balanced frequency response is the final solution to achieve quality speech reproduction. But sometimes it can still be beneficial if we use, for example, a speaker with a closed back. This way, we avoid possible sound reproduction rearwards - for example to a closed metal cabinet of the device, where unnecessary disturbing echoes could occur.
Also, depending on the application in which the speaker is placed, it is certainly interesting to know the operating temperature range of the speaker as well as the resistance to water and humid environments. These features also affect sound quality and lifetime of the speaker.
If you use a speaker in an industrial device, you will definitely be interested in specific solutions for quality speech transmission. As we continue with this article, we'll bring you 10 tips for speakers from Visaton's portfolio.
More information about Visaton products can be found on our website. We will be happy to answer to your suggestions and questions at sales@soselectronic.com
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