Introduction: The audible "click" for each several thousand cells emitted by early cell sorters allowed operators to monitor sort progression from afar (although within earshot). This was useful in releasing operators from their station during long sorts. I propose here that an enhanced version of this feature be re-introduced in current cytometers.
Methods: An audio output can be generated by the data acquisition software during acquisition or sorting. Each cell may be represented by a musical note, the pitch of which represents fluorescence intensity. Optionally, the volume of the note can reflect cell size. Thus, a characteristic "tune" is played by each cell sample flowing normally. In the event of partial or total nozzle blockage or sample exhaustion, the sorter would play a different tune that would be detected by an operator within earshot.
Discussion: It is further suggested that this technique can be developed from the simple monitor described above into an analytical tool. In modern multiple fluorescence analysis, many more cellular properties are measured than can be displayed at once. To augment the information conveyed in any visual display, a musical representation of parameters not displayed can be added. To the volume and pitch of each note can be added a unique "timbre" for each such parameter. Thus, for example, tubular bells may represent fluorescein, piano may represent phycoerythrin, etc. The number of instruments that can be individually recognized in this cellular symphony will depend upon the musical ear of the operator. A small computer program for testing this approach is available at http://www.wehi.edu.au/cytometry/freesoftware/.