Mobile Technology
The evolution of power and audio management
Udo Kratz looks at the latest wave of audio and power management innovations which are making audio and voice on smartphones sound better for longer and meeting changing consumer demand
O
ver the last ten years, there has been a convergence of media players with phones. The Sony-
Ericsson Walkman phone was the first evidence of a phone company offering media player capabilities, but this convergence really exploded with the launch of the first iPhone, the first instance of a media player company making a phone. Power consumption and the quality of audio had to change, and change dramatically. Today smartphones have become the primary media storage and playback device for the vast majority of consumers. At the same time, consumers want to be able to hold calls and use the smartphone’s speech-to-text and voice control applications even when there is a lot of loud, intrusive background noise. With the growing use of these “do it all devices” for a wider variety of business productivity and personal entertainment tasks, smartphone designers need to push the boundaries when it comes to battery life to enable longer use times. This is leading to a requirement for new, innovative approaches around power and audio management.
34 February 2014
The complex mixing and routing of mono and stereo signals (in analogue or digital formats) to and from the various internal and external speakers and headphones is handled by the smartphone’s audio ICs. The audio codec
analogue. It also often includes a dedicated audio/voice Digital Signal Processor (DSP) running a growing array of high performance voice and audio pre and post- processing software while reducing the power consumption. In this article, we look at three key consumer trends which are driving the development of new audio architectures, and explore the technology enabling manufacturers to meet these needs.
Wired for sound One of the main trends in this space is the increasing number of people using phones
speakers in their phones to play music. HTC one is one example of a new type of phone with greater emphasis on audio speakers (with its stereo front facing configuration).
Audio content needs to be recorded and played back in a wide variety of digital audio formats with various bit depths and sample rates.
Smartphones are no longer just being used for voice telephony, which typically has an 8 kHz sample rate, while multimedia uses sample rates ranging from 44.1kHz to 96kHz.
Staying in the game New gaming applications have the requirement to support 32 or more simultaneous audio streams and VoIP (Voice over Internet Protocol) for interactive game play or two-way video calls. Moreover many mobile network operators have started upgrading their networks to support HD Voice and some other operators have focused on stricter noise suppression requirements than before.
manages the process of switching between music, a ringtone and an incoming voice call, encoding analogue audio as digital signals and decoding digital back into
Components in Electronics
as a source for music. Hi-Fi quality docking stations and better headphones have driven up the expected/required audio quality, and more people are using
Packing an audio punch As more functionality is added into phones (e.g. cameras, motion sensors, touch screen, more powerful processors) the footprint of devices and the space inside the smartphone is becoming an important factor. In addition, consumers today expect to be able to enjoy a more resonant, full- bodied sound, regardless of whether they happen to like to listen to light pop, heavy rock or classical music. This, despite the
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