SignalSpy 1.1 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The software belongs to Audio & Video Tools. This Mac application is a product of Codelle. According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software.
From the developer:
SignalSpy is a suite of powerful tools that let you analyze audio signals. The app includes an oscilloscope, a spectrum analyzer, a level indicator, and a spectrogram. All tools are built for extreme accuracy, and thus, they can be used in studio applications. Many of the tools are configurable to adapt them to your needs.
You may want to check out more Mac applications, such as ImTOO DVD to iPhone Converter, StreamRipperX or Xilisoft iPhone Video Converter, which might be related to SignalSpy.