Dual Tones

The Dual Tones routine is used to generate a stimulus comprised of a series of tones, with the frequency, SPL, and duration time separately specified for phone 1 and phone 2. The successive tones generated will have the same frequency, SPL, etc., as the first tone of the series, for each phone. The following is a sample menu from the Dual Tones routine.

		Frequency 1 =   800.00 Hz
		      SPL 1 =       80 dB	atten 1 = 39 dB
		Frequency 2 =  1000.00 Hz
		      SPL 2 =       80 dB	atten 2 = 26 dB
	      Max for SPL 1 =      119 dB
	      Max for SPL 2 =      106 dB
		 Duration 1 =   300.00 msec
		 Duration 2 =  1000.00 msec
	    Repetition Time =  1500.00 msec
	    Delay of Master =   200.00 usec
	   Master DSS (1,2) =	     2
	    Refresh # Rep's =       10
	      Total # Rep's =       25
	    Phone (0,1,2,3) :        3
	      Spike display =        0
	     Number of bins =      200

w=W=Dset(newname), u=U=Dset(inc unit#), x=X=Dset(inc seq#)
p=P=CTRL-P=Pause, g=G=CTRL-G=Go, e=E=CTRL-Z=Exit, r=R=Retrieve, s=S=Store 

If the Spike Display parameter is set to 1, then a PST histogram will be displayed to show the cumulative spike response. The parameter Refresh # Rep's refers to the number of tone pips after which the display will be updated. The parameter Total # Rep's is the number of tone pips after which the histogram will be cleared and the DSS will be restarted. Note that the repetition time is the same for both phones - the time between the start of each successive tone. The Phone parameter is set to 0 for no phone, 1 for DSS 1, 2 for DSS 2, and 3 for both DSS 1 and 2.

The Delay of Master parameter allows for the stimulus of one of the DSS's to be presented at a slight delay after the stimulus of the other DSS. One must first specify the parameter Master DSS, as either 1 or 2. Then, depending on which DSS is chosen as the master, the delay will be placed on that DSS. Note that negative delays are allowed.

The Max for SPL 1 and Max for SPL 2 parameters are not set by the user, but are determined from the phone calibration curve and represent the maximum possible SPL values at the frequencies specified for phones 1 and 2, respectively.

Note that the input channel for collection of spikes through the UET (Unit Event Timer) is fixed as channel 0 for the Dual Tones routine. It is not currently possible to specify any other input channels.

The output display of the Dual Tones routine is a simple PST histogram. Because of the way this display is generated, there is currently no hardcopy option as with the other stimulus routines.

The arrow keys are used to move around in the menu. There are also several single-character commands available to the user at all times, while in the Dual Tones menu. They are listed here, and described in more detail below.

	g, G, or ^G	Start or restart stimulus
	p, P, or ^P	Stop stimulus, stay in Tone Pips menu
	e, E, or ^Z	Stop stimulus, return to SER main menu
	s or S		Store current menu params to special block
	r or R		Retrieve menu params stored by 's'
	w or W		Save current data, specify data set name
	u or U		Save current data, increment unit #
	x or X		Save current data, increment sequence #

After setting the parameters to the desired values, the series of tones is started by typing CTRL-G. At the end of the series (Total # Rep's), the display (if specified) will be cleared and the tones will be generated again. This continues until the user stops the stimulus. As with the FM Sweep routine, 'e' is used to exit, and 'p' stops the stimulus. Any individual parameter can be changed at any time -- type the new value, then hit 'Return' or one of the arrow keys to move the cursor. Then, stimulus will stop and restart with the new parameter values. Note that, as with the FM Sweep, it is can be faster to change a number of parameters by first typing 'p' to stop the stimulus, then modifying the parameters, then hitting 'g' to restart.

With the Dual Tones stimulus there is the special feature of a private storage block for the menu parameters. To store the current set of menu parameters into this storage block, type 's' or 'S'. Then, continue to run the stimulus, changing any parameter to a new value. To retrieve the set of parameters stored by the S command, type 'r' or 'R'.

Invalid parameter settings sometimes cause the stimulus to stop. The user must change the appropriate parameter(s), then type 'g' or CTRL-G to restart the stimulus.

To store the response data from the current series of tones, the user can type 'w', 'u', or 'x'. Each of these commands stores the data for the entire series of tones. The only difference between the 3 commands is how the name for the new data set is chosen. Each command displays the name of the most recently stored data set. The 'w' command prompts the user to type in a new name for the data set to be stored. The 'u' or the 'x' command will try to automatically create a new data set ID name. They look at the previous name, which is understood to have the format 'unit#-sequence#', preceded by an optional string of characters. For example, a valid name would be abc100-12, where the unit number is 100 and the sequence number is 12. The 'u' command will increment the unit number, and the 'x' command will increment the sequence number. If the previous data set name is not in this format, then each of the commands will prompt the user to type in a new data set id name.

The data for a series of Dual Tones are stored with the data set type name SRDU, which will distinguish it from data collected during one of the other stimulus options. The schema name for each data set is sch016.

See also the general description of the SER program.
See also the descriptions of the other SER stimulus options:
FM Sweep, Tone Pips, Clicks, Noise,