Hi Rona, thanks for your compliments on my videos and the music I use, I’m pleased you’ve found them helpful. Regarding the pulse-like sound you’ve been hearing, I’ve never had anyone report something similar to that before. I also haven’t heard anyone on brainwave entrainment forums mention it. That is very unusual and because I’ve never come across it before, I’m afraid I don’t know what would cause that.
One of the most fascinating and beneficial things about Delta brainwaves is their ability to stimulate the release of anti-aging hormones in the body, such as HGH (human growth hormone). Increased melatonin levels are also common in this state, and regular visits to Delta have also been shown to decrease cortisol levels. (Cortisol is a hormone that is released during stressful situations, that has been linked with the aging process.) In a nutshell, Delta brainwaves are very healthy, and until now have only been accessible to us during deep sleep.
The formal name for this process is called the “frequency following response”, where the human brain will literally “follow” a specific frequency/beat after being exposed to it for (usually) about 8 minutes.  Technically the definitive term “entrainment” does not exactly match the actual process of what is happening to your brain when listening to these audios, but its close enough, and the name has stuck now with these products becoming more popular and widely known.
A study published in Electroencephalography and Clinical Neurophysiology by Paul Williams and Michael West in 1975 examined the brainwave states of people experienced in meditation while using photic stimulation, and another study by Leonard, Telch, and Harrington in 1999 examined the successful use of brainwave entrainment techniques for attaining meditative states in subjects.
The same goes for brainwave entrainment.  You can’t just listen to an audio as many times as you want and expect that more is always better.  In a very real way, you are “exercising” your brain.  You are pushing it to build new neural pathways, to communicate with itself in new ways, and to adapt to a new kind of mental stimulation.  This is incredibly good for you, but there is a limit that you must observe.
* Supports iOS 5.0 and higher * Thanks for making Brain Wave the Top Selling Brainwave Entrainment app 4 years! This update includes improvements to our last major update, which included a ton of new features, including the ability to use your iTunes Music as the background and Alarm Audio, support for running another audio app simultaneously, such as a web or ebook reader, and UI updates for iOS 7.
With so many thoughts begging for your attention each day, it’s hard to believe that most of them are the same ones you had yesterday. Actually, many psychologists who have studied the thought processes associated with our thinking patterns would agree that, on average, 90% of the thoughts that we become aware of throughout the day are the same thoughts that we have already experienced, over and over again. The reason we are so prone to repetitive thinking is because the brain is always … [Read more...]
Your brain operates at certain levels of activity – the normal waking, active Beta, the meditative Alpha, the asleep-and-dreaming or deep meditative Theta, and the deep sleep/unconscious Delta. Beta is characterized by one thing we all want to get away from – stress.But that brainwave state has its place. It’s the action mode, and that’s the way it should be! If we’re not alert when we’re awake, bad things can happen, right?

Jump up ^ 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.
Research shows that parts of the brain and eventually large areas of the brain begin to resonate sympathetically with this "phantom" binaural beat. This is known as the Frequency Following Response. Subsequent research determined that a binaural beat frequencies drive brain activity into specific brain states. Thus, effortlessly and naturally, your brain activity slides into rhythm with this binaural beat, becoming organized and coherent. Within minutes, the sound frequencies start to balance the left and right hemispheres of your brain – creating a remarkable state called hemispheric synchronization and driving the electrical activity of your brain into powerful states, normally unattainable. Flashes of creative insight, euphoria and a deep sense of calm is often accompanied by this extraordinary brain state.
The phenomena of brainwave entrainment was first described in the scientific literature in 1973 by Gerald Oster in results published in an article in Scientific American entitled, “Auditory Beats in the Brain”. He showed that a specific brainwave could be induced when a person heard two separate, but closely related, sound frequencies, one in each ear. He discovered that when the frequencies heard by each ear differed by about 10 hertz, the brainwave pattern of the person hearing the sound would synchronize to the difference between the two frequencies. For example, if the person heard a 410 hertz sound in one ear and a 400 hertz sound in the other ear, their brainwaves would stabilize at the difference between the two, or 10 hertz. This technique is called binaural beats, and it is a fundamental principle of brainwave entrainment methods.
I enjoy this one called: Cognition Enhancer For Clearer and Faster Thinking – Isochronic Tones (Electronic) … I seem to enjoy it. Any harm in just listening to this one every day for 30 minutes as a routine daily thing, just like brushing your teeth and making your bed. I would just use it at times when I’m working at my desk, maybe even reading the online news etc…Thoughts?
This is the reason why I stress that one should ALWAYS read the instructions provided by the brainwave entrainment product creator, and always do their due diligence in researching the source of any products they purchase. When using a high quality product, these instructions are clear, precise, and always backed up by an extensive network of support and additional information. The product creators who have put in the necessary amount of effort and time to come up with a high quality product always make sure that you don’t get it wrong. 
That is very interesting to hear. I have also been an avid user of Holosync for long periods of my life. Were you progressing through the levels? I do know that Holosync in particular is designed for each level to push the brain to grow a “tolerance” to its effects. Once this happens the brain and nervous system has reached a new level of resiliency and is ready for the next level of the program, where the carrier frequencies are lower and more profound effects begin again. Was this the case for you? If Holosync was not your bag, you may also consider trying out some of the newer brainwave entrainment products with isochronic tones and monaural beats (holosync only uses binaural beats) as many have reported that they work better for them.
Leap over obstacles and hurdles, easily – Nothing worth having is ever easy. Everyone faces problems. The difference is, how you handle those problems. Imagine if you never even see them as problems to begin with... if it's just easy, somehow, to envisage simple solutions to hurdles and enjoy the challenge. Successful people thrive on challenges... you could begin to experience the very same rush!
Both brainwave entrainment and neurofeedback deal with brainwaves, but the similarity stops there. Entrainment pushes your whole brain into a pre-determined state, while neurofeedback teaches you how to move specific parts of your brain on your own. It is the differeence between forcing the brain into a given position, and skills building so you can move it there yourself.