This depends on how ready your brain is to absorb the impact of the tones and how responsive it is. Most people experience a feeling of relaxation and calm right from the first session. The degree to which you feel these hinges on how well your brain reacts. Use it over a few days and you can experience unmistakable signs of stress reduction and improved clarity of mind. After a while, when you brain gets trained in allowing better communication between the right and left hemispheres, you will sense that the feeling of mental clarity and calm carry forward even hours after a session.
The Delta brainwave is experienced by us every night in dreamless sleep. It is also experienced by advanced yogis and monks who can enter the Delta frequency during deep meditation. This frequency assists in both emotional and physical healing, as well as enhanced immune functioning, significant stress reduction, and even anti-aging benefits. The Delta frequency is a terrific way to experience deep repair on the physical, emotional, and psychological levels.
With the binaural beats, this may be difficult to do since you need to listen to the twin frequencies and allow your brain to create a third one to bridge the gap. Ideally, you will be listening to these beats through headphones so carrying out other work may be challenge. However, with isochronic frequencies, the tone can be heard without headphones which means you can run the mp3 with a speaker and allow it to play in the background as you carry out your work. Of course, activities such as driving or operating heavy machinery should NOT be undertaken when you are listening to these tones because your attention is shared between the two tasks. Tasks like gardening or sewing or cooking can be done while your brainwave entrainment music is playing.
Sleep and stress tend to cause a vicious cycle – if you’re stressed, then you can’t sleep, which makes you ill-prepared to handle the stressors of the next day, leading to more stress. To relieve stress before bed, try some relaxation techniques (see below) and disconnect from technology as much as possible an hour before bedtime. To ensure the proper amount of rest (7-8 hours is recommended), set an alarm reminding you to go to bed.
However, yoga and meditation take time to learn and master, and until the student becomes proficient, progress can be slow and frustrating, leading many people to abandon the effort before they see the benefits. Brainwave entrainment has the potential for helping a person enter the relaxing and rejuvenating mind-states brought about by yoga and meditation without the learning curve and time needed for mastering these other techniques. Brainwave entrainment may even facilitate learning other mindfulness methods by helping a person achieve success faster and more reliably. 
At Gaia Meditation, most of audio programs including free relaxation music, free sleep music, free meditation music etc. use the technology of brainwave entrainment (or “brainwave synchronization”) with powerful binaural beats and isochronic tones. Our audio tracks utilize pure and precisely tuned sound frequencies which will drive your brain activity (consciousness) into your desired state: Gamma, Beta, Alpha, Theta or Delta.

Delta brainwaves have the slowest frequencies, ranging between 0.1 and 4 hertz, and these are the brainwave states associated with deep sleep, trance states, and unconsciousness. Few people can remain awake during delta brainwaves states, although this state is recorded in awake infants between ages of three months and one year and also in babies just before birth. Delta waves are also linked with increased production of HGH, DHEA, and the neuro-transmitter serotonin.
Research shows that binaural beats can literally drive brain activity into specific brain states (Gamma, Beta, Alpha, Theta or Delta). Without any effort and naturally, you would have your brain activity to synchronize with the binaural beat; it will become organized and coherent, and eventually, the left and right hemispheres of your brain will start to be balanced creating a very unique state called “hemispheric synchronization” (equal frequency and amplitude of the wave forms in both hemispheres). This extraordinary brain state is very powerful and normally unattainable without this kind of stimulation. Through the entrainment of brain waves, binaural beats can influence the brain in a very subtle way, inducing states of relaxation, sleep, meditation, creativity…

Beta waves are the most common and most prevalent in the brain. These are the brain waves of alertness, dominating your normal waking state of consciousness. The Beta state relates to “fast” activity with neurons firing abundantly, in rapid succession, with attention focused directly towards cognitive tasks and the outside world. Beta activity is engaged in focused mental activity, problem solving, judgment and decision making. New ideas and solutions to problems flash like lightning into your mind.
When you play two separate frequencies in each ear, say 140 Hz and 149 Hz, the difference in frequency is 9 Hz. Your brain compensates for this difference and a third tone of 9 Hz is experienced. This will result in your brain being lowered or raised and tuned into the desired frequency. This is how binaural beats are produced. Headphones are essential for this to work.  
Monaural beats have similarities to binaural beats, but the two separate frequencies are delivered through a pulse pattern and mixed before they reach the listeners ears, resulting in the advantage of being audible without stereo headphones. However, using stereo headphones intensifies the effectiveness of monaural beats and is recommended for the best effect. 
For example, according to Wikipedia, if you take one frequency in one speaker in a pair of headphones, say, 300Hz, and the other speaker for your other ear has a frequency of 310Hz, the resulting difference of 10Hz would be the rate that the pulse, or beat, plays at. 10Hz (Alpha Waves) would correspond to what the brain puts out when you are generally relaxed. So, in effect, listening to a 10Hz binaural beat for a certain amount of time should take the edge off.
I wouldn’t personally recommend listening to delta wave frequencies for depression, so I’m not sure who advised you to do that? People with depression usually have a higher ratio of theta and delta wave activity, so I would normally recommend listening to high alpha wave and low beta wave frequencies, to help balance things. I have some 10Hz alpha tracks for serotonin release, which you can try for free on my YouTube channel here: I also recommend you give these SMR (low beta wave) tracks a try: I hope that helps.
Binaural beats were discovered in 1839 by a German experimenter, H. W. Dove. The human ability to "hear" binaural beats appears to be the result of evolutionary adaptation. Many evolved species can detect binaural beats because of their brain structure. The frequencies at which binaural beats can be detected change depending upon the size of the species' cranium. In the human, binaural beats can be detected when carrier waves are below approximately 1000 Hz (Oster, 1973). Below 1000 Hz the wave length of the signal is longer than the diameter of the human skull. Thus, signals below 1000 Hz curve around the skull by diffraction. The same effect can be observed with radio wave propagation. Lower-frequency (longer wave length) radio waves (such as AM radio) travel around the earth over and in between mountains and structures. Higher-frequency (shorter wave length) radio waves (such as FM radio, TV, and microwaves) travel in a straight line and can't curve around the earth. Mountains and structures block these high-frequency signals. Because frequencies below 1000 Hz curve around the skull, incoming signals below 1000 Hz are heard by both ears. But due to the distance between the ears, the brain "hears" the inputs from the ears as out of phase with each other. As the sound wave passes around the skull, each ear gets a different portion of the wave. It is this waveform phase difference that allows for accurate location of sounds below 1000 Hz(9). Audio direction finding at higher frequencies is less accurate than it is for frequencies below 1000 Hz. At 8000 Hz the pinna (external ear) becomes effective as an aid to localization. In summary it's the ability of the brain to detect a waveform phase difference is what enables it to perceive binaural beats.
Point #3 can easily be the case if you are still subscribing to the false idea that just listening to an entrainment track is meditation all by itself. Some unscrupulous marketing copy of various entrainment products uses phrases such as; “Our meditation CD meditates you…” which is of course, complete nonsense. I was asked recently to review one marketing ad which claimed, “With our meditation CDs you don’t need to know how to meditate…” This is worse than nonsense, it’s hogwash. That’s like saying, “If you use our wonderful plates and silverware you don’t even need to know how to cook.” If you believe that you’re unlikely to get many takers on your dinner invitations.
You might not realize it, but when you’re stressed, every muscle in your body tenses up. Taking a moment to recognize this and actively relaxing each part of your body can help. According to Whitaker, common stress-storing places are the jaw, neck, shoulders, back, and stomach. “The Instant Relaxation Technique is a deliberate tightening of the entire body, starting from the toes to the head region, and letting it go instantly,” Joshi says. “This is an effective way to become self-aware of our muscles and letting go of stress very quickly.” While you do this, picture all the negative emotion and tension leaving your body. Look out for these 8 silent signs stress is actually making you sick.
Thanks for the reply. I am now clearer on ‘what’ is heard. Can you expand or point me in direction ..a bit more about ‘pitch frequency’ and frequency spoken about and what exactly is the difference ..and how we use the higher pitch frequencies to ‘hear’ or become aware of them? Would you only pick up the low freq on a EEG?. sorry for being pedantic still does not clear up split isochronics and possibly creating same situation as binaural beats..
Anyone who has sought out different methods for enhancing cognitive ability will probably have come across a technique known as Brainwave Entrainment. However, it is a fairly niche area of brain training, meaning that this form of stimulation is often overlooked in favour of more mainstream methods. The following outlines what Brainwave Entrainment actually is, how it is used, and some of the benefits attributed to it.
In one study, researchers had a group of participants relax alone in a quiet, low-light environment following an exercise session. They split the group in two — one spent 20 minutes listening to theta-frequency binaural beats while the other listened to a carrier tone and monitored their parasympathetic (rest and relaxation) and sympathetic (fight or flight) nervous system activity. Researchers found the group that listened to binaural beats experienced an increase in parasympathetic activity and a decrease in sympathetic activity, along with higher rates of self-reported relaxation.
We may use the term “to meditate” as a convenience, but always keep in mind, what is really meant is that we enter into a state of meditation. It’s an important point to distinguish because if we get caught in the trap of regarding meditation “as a verb” it leads into all sorts of problems and misunderstandings. If a person incorrectly believes meditation is a verb, they generally also confuse whatever technique they use to arrive at a state of meditation as being meditation in and of itself.
Writing or talking about the things that prey on you—in a diary, with friends, in a support group or even a home computer file—helps you feel less alone and helpless. One study, published in The Journal of the American Medical Association, looked at people who had either rheumatoid arthritis or asthma— conditions known to be stress-sensitive. One group chronicled in a perfunctory manner the things they did each day. The other group was asked to write daily about what it was like, including fears and pain, to have their disease. What researchers found: People who wrote at length about their feelings had far fewer episodes of their illness.
Doing almost any routine, repetitive activity (like vacuuming, shredding paper or knitting), or reciting a word that represents how you wish you felt (such as calm) is a quick way to achieve a Zen-like state. Studies show the effects lower blood pressure and slow heart rate and breathing. The crucial elements are to focus on a word, your breathing or a movement and to bring your attention back to your task if your mind wanders or negative thoughts intrude. Or look to your faith for a mantra: A recent study published in the Journal of Advanced Nursing found that repeating phrases with spiritual meanings helped participants cope with a range of problems, from anxiety to insomnia.

The heart meditation is amazing. The recording of sound, vibration and guided words were heartfelt. I felt energy in waves as I listened and felt various sensations of heat, tingling, and muscular tension release as I become one with the recording.  A sincere thank you for making these recordings available to us in search of an enlightened path with the help of sound and vibration. 
On the other hand, if you’re a person who generally has their life together, and who is somewhat successful in your current coping strategies, even if they’re not perfect, then a little bit of additional quiet and relaxation may not seem so dramatic to you as it does to that burned out person. It will feel good, but the degree of difference between that and your normal way of life will not seem so extreme to you as it will to the burned out person. It is a relative experience.
Isochronic tones are basically just a single tone with the volume being turned on and off at regular intervals. When you apply the same effects to music or a noise, it’s usually referred to as amplitude entrainment effects (in Mind Workstation anyway). When you apply the on/off effect to music or noise it’s usually done by targeting a specific frequency range in the sound and only turning that part on/off, leaving the rest of the music/noise untouched. What that does is allow parts of the music/noise to play without being distorted/interrupted, making it sound more pleasant to listen to. It produces a kind of fluttering sound as I like to call it and you can adjust the level of intensity.

^ Trost W. and Vuilleumier P., Rhythmic entrainment as a mechanism for emotion induction by music: a neurophysiological perspective. In The Emotional Power of Music: Multidisciplinary Perspectives on Musical Arousal, Expression, and Social Control, Cochrane T., Fantini B., and Scherer K. R., (Eds.), Oxford, UK: Oxford University Press; 2013, pp213–225.