gusucode.com > 声音的处理有：LPC，FFT，共振峰，频谱源码程序 > siganlandsystemusingMatlab/SSUM/birds/old/birdsfn.m

    function birdsfn(action)

    if nargin < 1
        action='init';
    end

	% Add ability to see envelopes

    handles = get(gcf,'UserData');
    switch action
        case 'help'
            web(['file:' SSUMroot '/docs/help/birds.htm']);
	end