% Experiments conducted 16 Feb 2006 by Sean Hardesty and Erin Noel % One bead, pluck without lights n = 1; m = 0.125; % .5 oz sigma = 3.04*1.5; % 5.5 lb/mv*mv % units in cm -- reported by Scott ell0 = 24.5; % cm ell1 = 55; % cm a1 = sigma/2*(1/ell0+1/ell1); C = .5*m*eye(1); A = [ a1 ]; scale = (16)*(1/0.45359237) * (4.4482216162605) * (100); % (oz/lb)*(lb/kg) (N/lbf) (cm/m) % scale from Hardesty's calculator = 15690 B = scale*inv(C)*A; [V,D] = eig(B); rho = sqrt(diag(D)); freq = rho/(2*pi); fprintf('Predicted natural frequencies:\n') disp(freq) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % edited from Sean Hardesty's fftwav.m filename = 'record002.wav'; % plots time and frequency data for wav file filename % Sean Hardesty (1 Feb 2006) [y,fs]=wavread(filename); N=2^floor(log(length(y))/log(2)); if (N < 0.75*length(y)) N=length(y); end %use the next line if you have an old version of Matlab w=fft(y(1:N,:).*kron(sin((0:(N-1))*pi/N)',ones(1,size(y,2)))); % me % w=fft(y(1:N,:).*kron(window(@hamming,N),ones(1,size(y,2)))); range=(1:(N/2-1))'; f=range*fs/N; figure(1), clf phi = (sqrt(5)+1)/2; axes('position', [.125 .15 .75 phi-1]) ax = [0 140 1e-0 1e4]; mygridsemycoarse(ax, [0:20:ax(2)], [1e1 1e2 1e3]) for k=1:n plot(freq(k)*[1 1], ax(3:4),'k--','linewidth',1.5) end semilogy(f,abs(w(range,1)),'linewidth',1.5) xlabel('f (Hz)') title(sprintf('%s',filename)) axis(ax) set(gca,'xtick',[0:20:ax(2)]) print -depsc2 bead1b %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% figure(2), clf phi = (sqrt(5)+1)/2; axes('position', [.125 .15 .75 phi-1]) ax = [0 640 1e-2 1e4]; mygridsemycoarse(ax, [0:100:ax(2)], [1e-1 1e0 1e1 1e2 1e3]) for k=1:n plot(freq(k)*[1 1], ax(3:4),'k--','linewidth',1.5) end semilogy(f,abs(w(range,1)),'linewidth',1.5) xlabel('f (Hz)') title(sprintf('%s',filename)) axis(ax) set(gca,'xtick',[0:100:ax(2)]) print -depsc2 bead1b2