From 576e49d4289b99f5ad5ccce2feb5c555cc8190bd Mon Sep 17 00:00:00 2001
From: khannuuuuur <hsu.conner@gmail.com>
Date: Mon, 6 Dec 2021 09:01:44 -0800
Subject: [PATCH] added pitch shift envelope (file name amplifyFreqRange.m)

---
 src/amplifyFreqRange.m | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 src/amplifyFreqRange.m

diff --git a/src/amplifyFreqRange.m b/src/amplifyFreqRange.m
new file mode 100644
index 0000000..88adc8d
--- /dev/null
+++ b/src/amplifyFreqRange.m
@@ -0,0 +1,23 @@
+function output = amplifyFreqRange(input, fs, low, high, multiplier)
+    %Amplifies frequencies within a specified range, leaves all other
+    %frequencies the same.
+    %By Conner Hsu
+    
+    %input: 1D array representing the sound signal in the time domain
+    %fs: sampling frequency
+    %low: a scalar representing the lower bound of frequencies to be amplified
+    %high: a scalar representing the upper bound of frequencies to be amplified
+    %multiplier: a scalar that multiplies frequencies between low and high
+    %Returns modified signal in the time domain.
+    
+    len = length(input);
+    f = fs*(-len/2:len/2-1)/len;
+    
+    outputW = fftshift(fft(input));
+    for i = 1:length(outputW)
+       if (low < abs(f(i)) && abs(f(i)) < high)
+           outputW(i) = outputW(i)*multiplier;
+       end
+    end
+    output = real(ifft(fftshift(outputW)));
+end
\ No newline at end of file