100 Things #1: The ‘Stweep’ – SoundCheck’s Optimized Stepped Sine Sweep Stimulus

The Stweep test signal, one of the most efficient, accurate, noise-immune and flexible audio test signals in use today, was engineered by Steve Temme, Listen’s founder. It has been included in SoundCheck since the first version was released back in 1995. In this short video, we explain how it is different from the conventional stepped sine sweep used in most test systems and how its unique features enable shorter test times and excellent noise immunity for production environments.

The ‘Stweep’ – SoundCheck’s Optimized Stepped Sine Sweep Stimulus

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Read on about all of SoundCheck‘s stimulus options and more, with features perfect for R&D and Production.

Video Script:

The Stweep test signal, one of the most efficient, accurate, noise-immune and flexible audio test signals in use today, was engineered by Steve Temme, Listen’s founder. It has been included in SoundCheck since the first version was released back in 1995. 

So how is this different from the conventional stepped sine sweep used in most test systems?

A regular stepped sine sweep is not a continuous sweep – rather it plays a sine wave at discrete frequencies, step by step, within a user defined frequency range, and the user sets a resolution value to determine how many steps there will be.

SoundCheck’s ‘Stweep’ is an optimized stepped sine sweep that generates an integer number of cycles at each frequency step, ensuring a smooth “zero crossing” transition from step to step. This reduces transducer ringing and decreases settling time which yields faster and more accurate measurements. 

What makes it unique is that it is phase-continuous from frequency step to frequency step, in fact because of this, it sounds more like a sine chirp than a stepped sine. The Stweep can be user-configured with different resolutions to optimize the trade-off between stimulus duration and resolution.

Although the Stweep has been included in SoundCheck since 1995, it has more recently been refined to include a fast continuous sweep from one frequency to the next to further smooth the transitions, especially when the steps are large or when equalization is required.

It is innovations such as this that maintain the value of stepped sine signals as one of the most fundamental and powerful test stimuli in the audio analysis toolkit – the Stweep’s high speed and noise immunity make it an excellent choice for extremely fast production line measurements of parameters such as frequency response, phase, harmonics, and distortion measurements such as THD, Rub & Buzz and Perceptual Rub and Buzz. We’re just surprised that it’s only in the past year or so that other test system manufacturers have started to pay attention to this versatile stimulus.