Mobile Technology
fact they are using an ultra-thin smartphone that doesn’t have the space to accommodate the larger speakers that this would traditionally have required. These three key challenges are being
addressed with the evolution of new, advanced audio technologies:
• Intelligent sound processing with psychoacoustic bass boost SRS psychoacoustic bass boost can help to improve the loud speakers in ultra-thin smartphones. Simple physics dictate that as the surface area of a speaker cone gets smaller, the speaker's ability to reproduce low frequencies is reduced as it isn't able to move the necessary amount of air to reproduce those low frequencies at audible volumes. Many smartphone speakers have a low cut off frequency of several hundred Hertz, but the low bass notes are well below this in most music and will not be reproduced by the speaker, which is unappealing to the ear.
increasingly discerning consumers looking to use high specification headphones. The quality of headsets for smartphones has stepped up in quality from three to four years ago and many low sensitivity headphones are readily available in the marketplace. Wireless audio is another growing
trend, as it gives users a new level of freedom – whether they are listening to music, making phone calls or just need to hear clearly – and this flexibility is driving strong market growth. To be successful, wireless audio solutions need to deliver crystal-clear sound consistently in a variety of user set ups and with minimal hassle. This in turn requires a wireless technology capable of reliable, interference-free communication with good range and sufficient bandwidth. There are numerous wireless candidates, each with their own strengths and weaknesses. But there is one technology that is uniquely suited to the needs of
The solution is simple and ingenious;
there are ways to 'trick' the brain, into hearing frequencies that physically cannot be reproduced by a speaker. Psychoacoustic bass boost applies the overtones and undertones of the low frequencies to the mix. The brain then fills in the missing fundamentals, allowing the listener to perceive low frequencies. Psychoacoustic bass boost solutions, then, can enable small speakers to deliver big bass for a more enjoyable listening experience. Highly advanced digital processors can also incorporate multiband or parametric equalizers, and audio enhancements such as 3D surround effects, at the same processing speeds.
• Acoustic echo cancellation & noise suppression
Acoustic echo cancellation (AEC) and noise suppression (NS) is essential for phones that are likely to be used in handset or loudspeaker mode. This requires at least two microphones: one picks up the speaker’s voice with background noise, the other only background noise. The two audio signals are digitised by the audio codec and will differ in phase and amplitude, depending on which direction the noise is coming from, and the noise can be subtracted to provide a most intelligible call for the far end listener.
• Extending the dynamic range The dynamic range – describing the ratio of the softest sound to the loudest sound – has extended to around 100dB for the audio playback path. This means audio components need to be able to process signals with fewer losses at higher frequencies and with lower power consumption. This is very relevant for
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high-quality wireless audio: Digital Enhanced Cordless Telecommunications (DECT). By using the 20 MHz wide band range, centred around the dedicated to DECT 1.9 GHz band, DECT ULE doesn’t compete with other wireless signals and suffer from interference. A growing number of competing smart home devices share the over-crowded and unregulated 2.4GHz wireless band and devices can become slow and unresponsive when there is a lot of network traffic. For smartphone vendors, the trends are clear: more digital microphones, more audio interfaces, improved dynamic range, audio/voice processing and loudness for output transducers will enable consumers to enjoy the superior sound performance they want from their smartphone. Designing smartphones with combined power and audio management can offer a lower footprint compared to discrete solutions. At the same time, faster time to market is a key factor in the designs of power and audio in smartphones, as smartphone makers tend to typically refresh models every six months. Dialog is working with key players in the industry to meet these evolving audio criteria with its advanced power and audio management ICs, providing tools to support and accelerate the design phase to help manufacturers to get new models and solutions onto the market at swiftly as possible.
Dialog Semiconductor |
www.dialog-semiconductor.com
Udo Kratz is Senior Vice President and General Manager, Business Group Mobile Systems, at Dialog Semiconductor
Components in Electronics February 2014 35
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