diff --git a/core/actions.py b/core/actions.py
new file mode 100644
index 0000000..270f9ea
--- /dev/null
+++ b/core/actions.py
@@ -0,0 +1,43 @@
+class TimedAction:
+	
+	def __init__(self, start_t, duration_t, nodes, program):
+		
+		self.program = program
+		self.program.actions.append(self)
+		
+		if not isinstance(nodes, list):
+			nodes = [nodes]
+			
+		self.nodes = nodes # list of nodes
+		self.start_t = start_t
+		self.duration_t = duration_t
+		self.end_t = start_t + duration_t
+		
+	def tick(self, t):
+		
+		if t >= self.start_t and t <= self.end_t:
+			
+			for node in self.nodes:
+				
+				if t == self.start_t:
+					self.start(node)
+					
+				elif t == self.end_t:
+					self.end(node)
+					
+				else:
+					self.progress(t - self.start_t, node)
+	
+	# REIMPLEMENT
+	
+	def start(self, node):
+		
+		pass
+		
+	def end(self, node):
+		
+		pass
+		
+	def progress(self, rel_t, node):
+		
+		pass
\ No newline at end of file
diff --git a/core/nodes/sinenode.py b/core/nodes/sinenode.py
index 5e98cf5..598d021 100644
--- a/core/nodes/sinenode.py
+++ b/core/nodes/sinenode.py
@@ -1,6 +1,7 @@
 import math
 
 from ..soundnode import SoundNode
+from ..actions import TimedAction
 
 class SineNode(SoundNode):
 	
@@ -8,21 +9,52 @@ class SineNode(SoundNode):
 	
 		super().__init__("sine", room)
 		self.freqs = freqs
+		self.active = False
+		self.volume = 1
 		
-	def calc_freqs_volumes(self, t):
-		# This function returns volumes of each relevant freq
-		# at tick t
-		
-		res = dict()
-		for freq in self.freqs:
-			res[freq] = 1 / float(len(self.freqs))
-		return res
-		
-	def fill_amp_cache(self, t):
+	def calc_r_amps(self, t):
 		
+		if not self.active:
+			self.r_amps[t] = dict()
+			return
+			
 		tdct = dict()
-		for freq, vol in self.calc_freqs_volumes(t).items():
-			tdct[freq] = vol * math.sin(self.room.sine_multiplier * freq * t)
 		
-		self.amp_cache[t] = tdct
-		
\ No newline at end of file
+		for freq in self.freqs:
+			tdct[freq] = self.volume * math.sin(self.room.sine_multiplier * freq * t)
+		
+		self.r_amps[t] = tdct
+
+###
+		
+class PlayAction(TimedAction):	
+	
+	def __init__(self, start_t, duration_t, nodes, program):
+		
+		super().__init__(start_t, duration_t, nodes, program)
+		
+	def start(self, node):
+		
+		node.active = True
+		
+	def end(self, node):
+		
+		node.active = False
+		
+		
+class NoteAction(TimedAction):	
+	
+	def __init__(self, note, start_t, duration_t, nodes, program):
+		
+		super().__init__(start_t, duration_t, nodes, program)
+		self.note = note
+		
+	def start(self, node):
+		
+		note_freq = self.program.note_to_freq(self.note)
+		node.freqs = [note_freq]
+		node.active = True
+		
+	def end(self, node):
+		
+		node.active = False
\ No newline at end of file
diff --git a/core/nodes/sink.py b/core/nodes/sink.py
new file mode 100644
index 0000000..16208a5
--- /dev/null
+++ b/core/nodes/sink.py
@@ -0,0 +1,29 @@
+from ..soundnode import *
+
+class SinkNode(SoundNode):
+	
+	def __init__(self, name, room):
+	
+		super().__init__(name, room)
+	
+	def calc_r_amps(self, t):
+		
+		# This function returns volumes of each relevant freq
+		# at tick t
+		
+		res = dict()
+		
+		for source_node in self.wire_in:
+			for freq, vol in self.sample_r_amps_by_wire(source_node, t).items():
+				if not freq in res:
+					res[freq] = vol
+				else:
+					res[freq] += vol
+			
+		for source_node in self.air_in:
+			for freq, vol in self.sample_r_amps_by_air(source_node, t).items():
+				if not freq in res:
+					res[freq] = vol
+				else:
+					res[freq] += vol
+		self.r_amps[t] = res
\ No newline at end of file
diff --git a/core/program.py b/core/program.py
index 715c293..d65010c 100644
--- a/core/program.py
+++ b/core/program.py
@@ -1,15 +1,133 @@
+import os
+import wave
+
 from .room import Room
 
+
 class Program:
 	
-	def __init__(self):
+	NOTES_OF_OCTAVE = {
+		0: ['C', 'B#'],
+		1: ['C#', 'Db'],
+		2: ['D'],
+		3: ['D#', 'Eb'],
+		4: ['E', 'Fb'],
+		5: ['F', 'E#'],
+		6: ['F#', 'Gb'],
+		7: ['G'],
+		8: ['G#', 'Ab'],
+		9: ['A'],
+		10: ['A#', 'Bb'],
+		11: ['B', 'Cb']
+	}
+	
+	def __init__(self, name):
+		
+		self.name = name
+		self.room = Room()
+		self.volume = 0.1
+		self.actions = []
+		
+	def reset(self):
 		
 		self.room = Room()
 		
+	def note_to_freq(self, note):
+		
+		note_no = self.note_to_note_no(note)
+		return self.note_no_to_freq(note_no)
+		
+	def note_to_note_no(self, note):
+		
+		octave = int(note[-1])
+		note = note[:-1]
+	
+		note_no_oct = 1
+		for note_no_oct, notelst in self.NOTES_OF_OCTAVE.items():
+			
+			if note in notelst:
+				break
+		
+		corr_note_no_oct = note_no_oct - 8
+		return corr_note_no_oct + (octave*12)
+		
+	def note_no_to_freq(self, note_no):
+		
+		return 2**((note_no-49) / 12.0) * 440
+	
+	def st(self, t_sec):
+		# seconds to ticks
+		return self.room.sample_rate * t_sec
+		
+	def generate_frames(self, start_t_sec, end_t_sec):
+		
+		frames = []
+		
+		start_t = int(start_t_sec * self.room.sample_rate)
+		end_t = int(end_t_sec * self.room.sample_rate)
+			
+		for t in range(start_t, end_t):
+			
+			self.tick(t)
+			left_frame, right_frame = self.room.generate_frame(t)
+			
+			frames.append(left_frame)
+			frames.append(right_frame)
+	
+		return frames
+			
+	def write_frames_to_wavefile(self, frames, fn = 'export.wav'):
+		
+		with wave.open(fn, 'wb') as wav:
+			
+			wav.setnchannels(2)
+			
+			wav.setsampwidth(self.room.sample_width)
+			wav.setframerate(self.room.sample_rate)
+			wav.writeframes(b''.join(frames))
+			
+	def playback(self, start_t_sec, end_t_sec, fn = 'export.wav'):
+		
+		cmd = f'play -q --volume {self.volume} {fn} trim {start_t_sec} {end_t_sec-start_t_sec}'
+		os.system(cmd)
+		
+	def export(self, start_t_sec, end_t_sec, fn = "export.wav"):
+		
+		frames = self.generate_frames(start_t_sec, end_t_sec)
+		self.write_frames_to_wavefile(frames, fn=fn)
+		
+	def interface(self):
+		
+		print(f'\nRunning program: {self.name}')
+		print(f'[g 10] to generate 10 seconds')
+		print(f'[vol 10] to set playback volume to 10%')
+		print(f'[p 1 5] to play seconds 1 to 5')
+		
+		cmd = ''
+		while cmd != 'q':
+			cmd = input('\n[vol {self.volume*100}%]>> ')
+			
+			if cmd.startswith('g '):
+				end_sec = float(cmd[2:])
+				self.export(0, end_sec)
+				
+			if cmd.startswith('vol '):
+				vol = float(cmd[4:])
+				self.volume = vol / 100.0
+				
+			if cmd.startswith('p'):
+				pp = cmd.split(' ')
+				start_sec = float(pp[1])
+				end_sec = float(pp[2])
+				self.playback(start_sec, end_sec)
+	
+	def tick(self, t):
+		
+		for action in self.actions:
+			action.tick(t)
+		
+	# REIMPLEMENT THESE
+	
 	def setup(self):
 		
-		pass
-		
-	def tick(t):
-		
 		pass
\ No newline at end of file
diff --git a/core/room.py b/core/room.py
index 311b11a..50049dd 100644
--- a/core/room.py
+++ b/core/room.py
@@ -2,39 +2,13 @@ import wave
 import math
 
 from .soundnode import *
+from .nodes.sink import *
 
 TAU = 2 * math.pi
 
 def stb(i: int, bytelen: int) -> bytes:
 	return i.to_bytes(bytelen, byteorder='little', signed=True)
 
-class SinkNode(SoundNode):
-	
-	def __init__(self, name, room):
-	
-		super().__init__(name, room)
-	
-	def fill_amp_cache(self, t):
-		# This function returns volumes of each relevant freq
-		# at tick t
-		
-		res = dict()
-		
-		for source_node in self.wire_in:
-			for freq, vol in self.sample_freqs_by_wire(source_node, t).items():
-				if not freq in res:
-					res[freq] = vol
-				else:
-					res[freq] += vol
-			
-		for source_node in self.air_in:
-			for freq, vol in self.sample_freqs_by_air(source_node, t).items():
-				if not freq in res:
-					res[freq] = vol
-				else:
-					res[freq] += vol
-					
-		self.amp_cache[t] = res
 
 class Room:
 	
@@ -42,13 +16,15 @@ class Room:
 		
 		self.nodes = []
 		
-		self.dissipation_quotient = 0.9993
 		self.sample_rate = 44100
 		self.speed_of_sound = 343 / float(self.sample_rate) # m/tick
 		self.set_bit_depth(24)
 	
-		self.left_sink = SinkNode('LEFT', self)
-		self.right_sink = SinkNode('RIGHT', self)
+		self.left_sink  = SinkNode('left', self)
+		self.left_sink.start_location = (-0.3, 0, 0)
+		
+		self.right_sink = SinkNode('right', self)
+		self.right_sink.start_location = (0.3, 0, 0)
 		
 		self.sine_multiplier = TAU / self.sample_rate
 		
@@ -61,151 +37,57 @@ class Room:
 		self.min_amp = -int((2**bit_depth) / 2.0)
 		self.sample_width = int(self.bit_depth / 8.0)
 		
+	def generate_frame(self, t):
 		
-	def generate_frames(self, start_t_sec, end_t_sec):
-		
-		frames = []
-		
-		start_t = start_t_sec * self.sample_rate
-		end_t = end_t_sec * self.sample_rate
+		for node in self.nodes:
+			node.tick_done = False
+				
+		if t%1000 == 0:
+			print(t, end='\r', flush=True)
 			
-		for t in range(start_t, end_t):
-						
-			if self.running_program:
-				self.running_program.tick(t)
+		updates = True
 		
+		while updates:
+			
+			updates = False
+			
 			for node in self.nodes:
-				node.tick_done = False
+				
+				if not (t in node.r_amps):
 					
-			if t%1000 == 0:
-				print(t)
-				
-			updates = True
-			
-			while updates:
-				
-				updates = False
-				
-				for node in self.nodes:
+					has_unprocessed_inputs = False
 					
-					if not (t in node.amp_cache):
-						
-						has_unprocessed_inputs = False
-						
-						for in_node in node.air_in:
+					for in_node in node.air_in:
+						if not in_node.tick_done:
+							has_unprocessed_inputs = True
+							break
+					
+					if not has_unprocessed_inputs:
+						for in_node in node.wire_in:
 							if not in_node.tick_done:
 								has_unprocessed_inputs = True
 								break
+								
+					if not has_unprocessed_inputs:
 						
-						if not has_unprocessed_inputs:
-							for in_node in node.wire_in:
-								if not in_node.tick_done:
-									has_unprocessed_inputs = True
-									break
-									
-						if not has_unprocessed_inputs:
-							
-							node.fill_amp_cache(t)
-							node.tick_done = True
-							updates = True
-		
-			left_total_amp = self.max_amp * sum([vol for freq, vol in self.left_sink.amp_cache[t].items()])
-			right_total_amp = self.max_amp * sum([vol for freq, vol in self.right_sink.amp_cache[t].items()])
-			
-			if left_total_amp > self.max_amp:
-				left_total_amp = self.max_amp
-				
-			if left_total_amp < self.min_amp:
-				left_total_amp = self.min_amp
-			
-			if right_total_amp > self.max_amp:
-				right_total_amp = self.max_amp
-				
-			if right_total_amp < self.min_amp:
-				right_total_amp = self.min_amp
-			
-			frames.append(stb(int(left_total_amp), self.sample_width))
-			frames.append(stb(int(right_total_amp), self.sample_width))
+						node.calc_r_amps(t)
+						node.tick_done = True
+						updates = True
 	
-		return frames
-			
-	def write_frames_to_wavefile(self, fn, frames):
+		left_total_amp = self.max_amp * sum([vol for freq, vol in self.left_sink.r_amps[t].items()])
+		right_total_amp = self.max_amp * sum([vol for freq, vol in self.right_sink.r_amps[t].items()])
 		
-		with wave.open(fn, 'wb') as wav:
+		if left_total_amp > self.max_amp:
+			left_total_amp = self.max_amp
 			
-			wav.setnchannels(2)
-			
-			wav.setsampwidth(self.sample_width)
-			wav.setframerate(self.sample_rate)
-			wav.writeframes(b''.join(frames))
-			
-	def record(self, fn, start_t_sec, end_t_sec):
+		if left_total_amp < self.min_amp:
+			left_total_amp = self.min_amp
 		
-		frames = self.generate_frames(start_t_sec, end_t_sec)
-		self.write_frames_to_wavefile(fn, frames)
+		if right_total_amp > self.max_amp:
+			right_total_amp = self.max_amp
+			
+		if right_total_amp < self.min_amp:
+			right_total_amp = self.min_amp
 		
+		return stb(int(left_total_amp), self.sample_width), stb(int(right_total_amp), self.sample_width)
 		
-	"""	
-	def record(self, fn, start_t_sec, end_t_sec):
-		
-		with wave.open(fn, 'wb') as wav:
-			
-			wav.setnchannels(2)
-			
-			self.sample_width = int(self.bit_depth / 8.0)
-			wav.setsampwidth(self.sample_width)
-			wav.setframerate(self.sample_rate)
-			
-			frames = []
-			
-			start_t = start_t_sec * self.sample_rate
-			end_t = end_t_sec * self.sample_rate
-			
-			for t in range(start_t, end_t):
-				
-				#№if t%1000 == 0:
-				#	print(t)
-				f = self.lowest_freq
-				
-				left_total_amp = 0
-				right_total_amp = 0
-				
-				left_amps = []
-				right_amps = []
-				
-				while f < self.highest_freq:
-					
-					for in_node in self.left_sink.air_in:
-						left_amps.append(in_node.amp_at_tick_by_air(f, t, self.left_sink))
-					
-					for in_node in self.left_sink.wire_in:
-						left_amps.append(in_node.amp_at_tick(f, t))
-					
-					for in_node in self.right_sink.air_in:
-						right_amps.append(in_node.amp_at_tick_by_air(f, t, self.right_sink))
-					
-					for in_node in self.right_sink.wire_in:
-						right_amps.append(in_node.amp_at_tick(f, t))
-						
-					f += self.freq_sample_step
-					
-				left_total_amp = self.max_amp * sum(left_amps)
-				right_total_amp = self.max_amp * sum(right_amps)
-				
-				if left_total_amp > self.max_amp:
-					left_total_amp = self.max_amp
-					
-				if left_total_amp < self.min_amp:
-					left_total_amp = self.min_amp
-				
-				if right_total_amp > self.max_amp:
-					right_total_amp = self.max_amp
-					
-				if right_total_amp < self.min_amp:
-					right_total_amp = self.min_amp
-				
-				frames.append(stb(int(left_total_amp), self.sample_width))
-				frames.append(stb(int(right_total_amp), self.sample_width))
-				
-			wav.writeframes(b''.join(frames))
-	"""
\ No newline at end of file
diff --git a/core/soundnode.py b/core/soundnode.py
index 689602a..72e0831 100644
--- a/core/soundnode.py
+++ b/core/soundnode.py
@@ -9,22 +9,17 @@ class SoundNode:
 		self.room = room
 		self.room.nodes.append(self)
 		
-		self.amp_cache = dict() # {tick: {freq: amp}}
+		self.r_amps = dict() # {tick: {freq: r_amp}}
 		
 		self.air_in = []
 		self.wire_in = []
 		
 		self.start_location = (0, 0, 0)
 		
+		# Used by the tick cycle to correctly order the nodes.
+		# Do not touch this.
 		self.tick_done = False
 		
-	def location(self, t):
-		
-		# Location of the soundnote (x,y,z) in meters
-		# at time t.
-		
-		return self.start_location
-			
 	def distance_to_node(self, other_node, t):
 		
 		loc = self.location(t)
@@ -32,49 +27,47 @@ class SoundNode:
 	
 		return (loc[0]-other_loc[0])**2 + (loc[1]-other_loc[1])**2 + (loc[2]-other_loc[2])**2
 	
+	def sample_r_amps_by_wire(self, source_node, current_t):
 		
-	def fill_amp_cache(self, t):
-	
-		self.amp_cache[t] = dict()
-		
-	def sample_freqs_by_wire(self, source_node, current_t):
-		
-		if current_t in source_node.amp_cache:
-			return source_node.amp_cache[current_t]
+		if current_t in source_node.r_amps:
+			return source_node.r_amps[current_t]
 			
 		return dict()
-		
-	def sample_freqs_by_air(self, source_node, current_t):
+	
+	def sample_r_amps_by_air(self, source_node, current_t):
 		
 		dist = self.distance_to_node(source_node, current_t)
 		sample_t = current_t - int(dist / self.room.speed_of_sound)
 		
-		if sample_t in source_node.amp_cache:
-			return {f: a / float(dist) for f, a in source_node.amp_cache[sample_t].items()}
+		if sample_t in source_node.r_amps:
+			return {f: a / float(dist) for f, a in source_node.r_amps[sample_t].items()}
 			
 		return dict()
 		
-	def add_air_output(self, out_node):
+	def air_to(self, out_node):
 		
 		if not self in out_node.air_in:
 			out_node.air_in.append(self)
 	
-	def add_wire_output(self, out_node):
+	def wire_to(self, out_node):
 		
 		if not self in out_node.wire_in:
 			out_node.wire_in.append(self)
 			
-	"""
+	## THE FOLLOWING FUNCTIONS NEED TO BE DEFINED BY CONCRETE NODES
+	
+	def location(self, t):
 		
-	def amp_at_tick(self, f, t):
+		# Location of the soundnote (x,y,z) in meters
+		# at time t.
 		
-		return self.frequency_max_rel_amp(f, t) * math.sin(self.room.sine_multiplier * f * t)
+		return self.start_location
+			
+	def calc_r_amps(self, t):
 		
-	def amp_at_tick_by_air(self, f, t, node):
+		# Fill the amp_cache for tick t
+		# {freq: relative_amp}
+		# relative_amp must be between 0 and 1
 		
-		dist = self.distance_to_node(node, t)
-		t = t - int(dist / self.room.speed_of_sound)
-		
-		return self.frequency_max_rel_amp(f, t) * math.sin(self.room.sine_multiplier * f * t)
-	"""
+		self.r_amps[t] = dict()
 	
\ No newline at end of file
diff --git a/test.py b/test.py
index cd8d428..453bc56 100644
--- a/test.py
+++ b/test.py
@@ -1,21 +1,42 @@
-from core.room import Room
-from core.prorgam import Program
-from core.soundnode import SoundNode
-from core.nodes.sinenode import SineNode
 import math
 
-R = Room()
-R.left_sink.start_location = (-1, 0, 0)
-R.right_sink.start_location = (2, 0, 0)
+from core.room import Room
+from core.program import Program
+from core.soundnode import SoundNode
+from core.nodes.sinenode import *
 
-sn = SineNode([440, 440*2, 440*3, 440*4, 220], R)
-sn2 = SineNode([523.25, 523.25*2, 523.25*3, 523.25*4, 220], R)
+class TestProgram(Program):
+	
+	def __init__(self):
+		
+		super().__init__("testprogram")
 
-sn.add_air_output(R.left_sink)
-sn.add_air_output(R.right_sink)
-sn2.add_air_output(R.left_sink)
-sn2.add_air_output(R.right_sink)
-sn2.start_location = (1, 0, 0)
+	def setup(self):
+		
+		self.reset()
+		
+		sn = SineNode([], self.room)
+		
+		sn.air_to(self.room.left_sink)
+		#sn.air_to(self.room.right_sink)
+		
+		NoteAction('A4', self.st(0), self.st(0.5), [sn], self)
+		NoteAction('G4', self.st(1), self.st(0.5), [sn], self)
+		NoteAction('F4', self.st(2), self.st(0.5), [sn], self)
+		NoteAction('E4', self.st(3), self.st(0.5), [sn], self)
+		
+		sn2 = SineNode([], self.room)
+		
+		#sn2.air_to(self.room.left_sink)
+		sn2.air_to(self.room.right_sink)
+		
+		NoteAction('A3', self.st(0), self.st(0.5), [sn2], self)
+		NoteAction('G3', self.st(1), self.st(0.5), [sn2], self)
+		NoteAction('F3', self.st(2), self.st(0.5), [sn2], self)
+		NoteAction('E3', self.st(3), self.st(0.5), [sn2], self)
 
 
-R.record('test6.wav', 0, 2)
\ No newline at end of file
+
+TP = TestProgram()
+TP.setup()
+TP.interface()
\ No newline at end of file