diff --git a/ITU_P56.py b/ITU_P56.py
index 7e6291e..6952cea 100644
--- a/ITU_P56.py
+++ b/ITU_P56.py
@@ -31,6 +31,7 @@ def asl_P56(x, fs, nbits):
     H = 0.2  # hangover time in seconds
     M = 15.9  # margin in dB of the difference between threshold and ASL
     thres_no = nbits-1  # number of thresholds, for 16 bit, it's 15
+    c0 = None
 
     I = np.ceil(fs*H)  # hangover in samples
     g = np.exp(-1/(fs*T))  # smoothing factor in envelop detection
diff --git a/eeg_test_thread.py b/eeg_test_thread.py
index 3a3be14..aeb053b 100644
--- a/eeg_test_thread.py
+++ b/eeg_test_thread.py
@@ -12,6 +12,7 @@ from shutil import copy2
 import re
 import sounddevice as sd
 from ITU_P56 import asl_P56
+from snrops import rms_no_silences
 
 from hearing_loss_sim import apply_hearing_loss_sim
 from test_base import BaseThread, run_test_thread
@@ -250,15 +251,17 @@ class EEGTestThread(BaseThread):
 
             speech = audio[:, :2]
             triggers = audio[:, 2]
-            speech_rms, _, _ = asl_P56(speech, fs, 16.)
+            #speech_rms, _, _ = asl_P56(speech, fs, 16.)
+            rms_no_silences(speech, fs, -30.)
+
             wf = []
             wm = []
             for ind2, s in enumerate(snr):
                 start = randint(0, noise_file.frames()-speech.shape[0])
                 noise_file.seek(start)
                 noise = noise_file.read_frames(speech.shape[0])
-                #noise_rms = np.sqrt(np.mean(noise**2))
-                noise_rms = asl_P56(noise, fs, 16)
+                noise_rms = np.sqrt(np.mean(noise**2))
+                # noise_rms = asl_P56(noise, fs, 16)
                 snr_fs = 10**(-s/20)
                 if snr_fs == np.inf:
                     snr_fs = 0.
diff --git a/matrix_test/behavioural_stim/gen_noise.py b/matrix_test/behavioural_stim/gen_noise.py
index 3c199ae..117fd12 100755
--- a/matrix_test/behavioural_stim/gen_noise.py
+++ b/matrix_test/behavioural_stim/gen_noise.py
@@ -20,6 +20,7 @@ from pysndfile import PySndfile, sndio
 import matplotlib.pyplot as plt
 from ITU_P56 import asl_P56
 from pathlib import Path
+from snrops import rms_no_silences
 
 from multiprocessing.dummy import Pool as ThreadPool
 import multiprocessing
@@ -215,7 +216,8 @@ def gen_noise(OutDir, b, fs):
     y = noise_norm_wav.read_frames(fs*60)
     y = y/(np.abs(y).max() * 0.95)
     # rms = np.sqrt(np.mean(y**2))
-    rms, _, _ = asl_P56(y, fs, 16)
+    # rms, _, _ = asl_P56(y, fs, 16)
+    rms = rms_no_silences(y, fs, -30.)
     print(f"Noise level: {rms}")
 
     peak = np.abs(y).max()
@@ -235,7 +237,9 @@ def calc_speech_rms(files, silences, rmsDir, fs=44100, plot=False):
     def level_calc(args):
         ind, wavfile = args
         x, fs, _ = sndio.read(wavfile)
-        level = asl_P56(x, fs, 16.)[0]
+        # level = asl_P56(x, fs, 16.)[0]
+        level = rms_no_silences(x, fs, -30.)
+
         print(f"Calculated level of {Path(wavfile).name} ({ind+1}/{n_files}): {level}")
         return level
 
diff --git a/matrix_test/helper_modules/signalops.py b/matrix_test/helper_modules/signalops.py
index bd961f0..6c1a6b0 100644
--- a/matrix_test/helper_modules/signalops.py
+++ b/matrix_test/helper_modules/signalops.py
@@ -147,10 +147,9 @@ def gen_trigger(x, freq, length, fs):
 
 def calc_rms(y, window, plot=False):
     y_2 = y**2
-    rms = np.zeros(y_2.size + round(window/2.))
+    y_2 = np.pad(y_2, (round(window/2.)-1, round(window/2.)), 'constant', constant_values=(0, 0))
     y_i = rolling_window_lastaxis(y_2, window)
-    for ind, frame in enumerate(y_i):
-        rms[ind+round(window/2.)] = np.sqrt(np.mean(frame))
+    rms = np.sqrt(np.mean(y_i, axis=1))
     rms[np.isnan(rms)] = 0
     if plot:
         plt.plot(y)
diff --git a/matrix_test_thread.py b/matrix_test_thread.py
index 02d363c..eae1cee 100644
--- a/matrix_test_thread.py
+++ b/matrix_test_thread.py
@@ -19,6 +19,8 @@ from matrix_test.helper_modules.filesystem import globDir
 from test_base import BaseThread
 import sounddevice as sd
 import pdb
+from ITU_P56 import asl_P56
+from snrops import rms_no_silences
 
 from config import socketio
 from hearing_loss_sim import apply_hearing_loss_sim
@@ -400,7 +402,8 @@ class MatTestThread(BaseThread):
                     # Read in audio file and calculate it's RMS
                     x, self.fs, _ = sndio.read(fp)
                     logger.info(f"Calculating level for {Path(fp).name}")
-                    x_rms, _, _ = asl_P56(x, self.fs, 16.)
+                    # x_rms, _, _ = asl_P56(x, self.fs, 16.)
+                    x_rms = rms_no_silences(x, self.fs, -30.)
                     self.lists[-1].append(x)
                     self.listsRMS[-1].append(x_rms)
                     self.listsString[-1].append(words)
@@ -537,8 +540,10 @@ class AdaptiveTrack():
         end = start + noiseLen
         self.noise.seek(start)
         x_noise = self.noise.read_frames(end-start)
+        # x_rms = np.sqrt(np.mean(x**2))
         # Scale noise to match the RMS of the speech
-        x_noise *= x_rms/self.noise_rms
+        noise_rms = np.sqrt(np.mean(x_noise**2))
+        x_noise *= x_rms/noise_rms
         y = x_noise
         # Set speech to start 500ms after the noise, scaled to the desired SNR
         sigStart = random.randint(round(self.fs/2.), round(2*self.fs))
diff --git a/rms_test.py b/rms_test.py
new file mode 100644
index 0000000..07a76e5
--- /dev/null
+++ b/rms_test.py
@@ -0,0 +1,11 @@
+from pysndfile import sndio
+from snrops import rms_no_silences
+
+def main():
+    x, fs, enc = sndio.read('./matrix_test/behavioural_stim/stimulus/wav/sentence-lists/ukmatrix10.1/Trial_00001.wav')
+    rms = rms_no_silences(x, fs, -30)
+    breakpoint()
+
+
+if __name__ == '__main__':
+    main()
diff --git a/snrops.py b/snrops.py
new file mode 100644
index 0000000..f1e7034
--- /dev/null
+++ b/snrops.py
@@ -0,0 +1,39 @@
+import sys
+sys.path.insert(0, "matrix_test/helper_modules")
+import numpy as np
+from signalops import rolling_window_lastaxis, calc_rms
+
+
+def detect_silences(x, fs, threshold=-30.):
+    print("Detecting silence in wav files...")
+    if len(x.shape) < 2:
+        x = x[:, np.newaxis]
+    x = x.sum(axis=1)/2.
+    env = calc_rms(x, window=int(fs*0.1))
+    threshold = (10**(threshold/20.))*np.max(env)
+    silence = env < threshold
+    # Get segment start end indexes for all silences in envelope
+    sil_start = np.where(np.sign(np.diff(silence.astype(float))) == 1)[0]
+    sil_end = np.where(np.sign(np.diff(silence.astype(float))) == -1)[0]
+    if silence[0]:
+        sil_start = np.concatenate([[0], sil_start])
+    if silence[-1]:
+        sil_end = np.concatenate([sil_end, [env.size]])
+    segs = np.vstack([sil_start, sil_end]).T
+    validSegs = np.diff(segs) > 0.02*fs
+    segs = segs[np.repeat(validSegs, 2, axis=1)].reshape(-1, 2)
+    return segs
+
+
+def slices_to_mask(slices, mask_length):
+    out = np.zeros(mask_length, dtype=bool)
+    for s in slices:
+        out[s[0]:s[1]] = True
+    return out
+
+
+def rms_no_silences(x, fs, threshold):
+    silences = detect_silences(x, fs, threshold)
+    sil_mask = slices_to_mask(silences, x.size)
+    rms = np.sqrt(np.mean(x[~sil_mask]**2))
+    return rms